A mix of personal experience and reading the news regularly & seeing the problems it causes for other people. It's been a very long time since I updated this list so I've just had to do a quick search to add some more recent events (and it's not a complete list, and it's not entirely in chronological order), but:

http://www.theregister.co.uk/2006/03/18/ms_drm_plays_for_shorter/

http://www.theregister.co.uk/2008/04/30/eff_msn_music_open_letter/

http://www.theregister.co.uk/2008/07/18/ubisoft_pirates_fix_from_pirates/

http://www.theregister.co.uk/2008/07/25/yahoo_announces_death_of_drm_servers/

http://www.theregister.co.uk/2008/07/29/yahoo_to_reimburse_drm_prisoners/

http://www.theregister.co.uk/2009/07/18/amazon_removes_1984_from_kindle/

http://social.bioware.com/forum/Dragon-Age-II/Dragon-Age-II-PC-Technical-Self-Help/Activation-saying-Offline-when-clearly-im-not-6462079-1.html

http://www.escapistmagazine.com/news/view/98927-Ubisoft-DRM-Authentication-Servers-Go-Down

http://www.theregister.co.uk/2010/03/08/ubisoft_anti_drm_hack_attack/

http://www.escapistmagazine.com/news/view/108394-No-Dragon-Age-2-for-Suspended-BioWare-Forumite-UPDATED

http://www.escapistmagazine.com/news/view/99566-Australian-Gamers-Struggling-Under-Ubisoft-DRM

http://www.escapistmagazine.com/news/view/99770-Settlers-7-DRM-Problems-Still-Unresolved

http://www.rockpapershotgun.com/2010/05/12/max-embarassment-max-payne-2-steam/

http://www.rockpapershotgun.com/2011/04/13/imagine-that-ea-drm-goes-haywire/
http://www.escapistmagazine.com/news/view/109218-DRM-Server-Failure-Knocks-Out-Dragon-Age-DLC-for-Days-UPDATED

http://arstechnica.com/gaming/news/2011/04/drm-run-amok-how-bioware-and-ea-are-screwing-users-right-now.ars

http://www.escapistmagazine.com/news/view/109999-Indie-RPG-Veteran-Being-Nice-Prevents-Piracy-Better-Than-Draconian-DRM

http://www.thewitcher.com/community/entry/35 : "...DRM adds another layer of complication and potential problems. We saw this clearly in our game. Pre-release tests showed only small performance differences compared to the DRM-free (GOG.com) versions. We were unpleasantly surprised when some of our fans reported much larger differences, up to 30% lower framerates..."

http://arstechnica.com/gaming/news/2011/08/ubisoft-lied-about-from-dust-drm-ubis-war-on-pc-gamers-continues.ars : "To add insult to injury, the game has already been successfully cracked, making the activation requirement apply only to paying customers. Pirates, once again, get a fully functional version of the game."

http://kotaku.com/5845866/origin-account-bans-threatened-for-playing-on-modded-battlefield-3-beta-servers

http://www.reghardware.com/2011/10/03/apple_tv_owners_lose_legal_movie_playback/

http://kotaku.com/5858473/steam-hacked-valve-investigating-possible-credit-card-theft

http://www.rockpapershotgun.com/2011/09/06/avalanche-on-drm-doesnt-nothing-useful/
http://www.escapistmagazine.com/news/view/108748-Avalanche-Studios-Boss-Reveals-Secret-Plan-to-Stop-Piracy

http://www.rockpapershotgun.com/2011/10/27/darkspore-drm-shuts-out-new-players/

http://www.rockpapershotgun.com/2012/01/16/ubisofts-activations-monitor-hardware-changes/
http://www.escapistmagazine.com/news/view/115298-PC-Upgrades-Trigger-Ubisoft-Activation-Limits

http://www.rockpapershotgun.com/2012/01/19/ubisoft-anno-2070-drm-works-as-intended/

http://www.rockpapershotgun.com/2012/01/25/fred-wester-drm-is-a-waste-of-money/

http://www.rockpapershotgun.com/2012/02/01/thought-do-we-own-our-steam-games/

http://www.rockpapershotgun.com/2012/02/02/legitimate-ubisoft-games-wont-work-tues/

http://www.escapistmagazine.com/news/view/117151-Diablo-III-Launch-May-Get-Messy

http://www.escapistmagazine.com/news/view/117262-Server-Issues-Mar-Diablo-IIIs-Launch

http://www.escapistmagazine.com/news/view/118300-DRM-Kills-Angry-Birds

http://www.escapistmagazine.com/news/view/118778-Update-Major-Security-Hole-Found-in-Ubisofts-PC-Titles

http://www.theregister.co.uk/2012/11/07/microsoft_drm_spy_patent/

http://www.escapistmagazine.com/news/view/120850-GameMaker-Studio-DRM-Bug-Trashes-Legit-Resources

http://www.rockpapershotgun.com/2012/11/30/far-cry-3-servers-down-already-ubi-this-is-a-mess/

http://www.rockpapershotgun.com/2013/03/05/gamers-line-up-to-play-simcity/

https://www.techdirt.com/articles/20130307/17202922246/just-cause-2-developer-why-it-wont-utilize-drm-it-treats-our-fans-like-criminals.shtml

http://www.rockpapershotgun.com/2013/03/11/simcity-is-inherently-broken-lets-not-let-this-go/

http://www.theregister.co.uk/2013/03/19/ea_origin_bug_allows_remote_exploits/

http://www.theregister.co.uk/2013/05/09/tor_says_no_piracy_increase_without_drm/

http://www.theregister.co.uk/2013/05/22/acetrax_closure_drm_woes/

It's the principle of the thing. If you don't understand that, then why are you here?

Until you've been denied playing games for the night through Steam screwing up their updates and instead spent gaming time fixing Steam, have needed to file a BBB claim to simply get your password changed on Steam to play your copy of Super Meat Boy that you bought on CD *intentionally* to avoid this sort of rigamarole; forcing you to pirate a game you bought legitimately, or have been required to login to Steam at a time your internet is out to play a single-player game, (and these are just my Steam stories) you frankly don't know what the hell you're talking about.

The only people DRM hurts is the honest customers. Pirates have none of these problems and, to them, the game is cracking the DRM. This is the entire impetus behind the no-DRM here. I'm amazed that anyone can be here and not understand this concept. Your party-of-one confirmation-bias hardly represents the world at large nor does it represent even a modicum of theory-of-mind/understanding of experiences other than your own. There's millions of other gamers out there. Christ, there's thousands, if not more, just here alone.

That there on the floor... <points>. There's your dignity.

As far as Bioshock's DRM issues are concerned, it's a thing of the past at this point. It does its activation and then you're good. In the past there were a limited number of activations which some people took issue with, and I can understand why. But, it still doesn't hurt at all to crack it as I mentioned above. Then it at least runs without the DVD. Steam technically accomplishes the same thing, but you'll never see me advocate Steam. I also can't speak for whether you can run it without Steam being logged in to.

Well said.

Just installed Bioshock 1 on Steam this evening, so I started it up, quit out, then ran the Securom removal tool. It picked up no trace of Securom DRM. I also checked the registry and no Securom registry entries were created.

From this, I'm taking it that the third party DRM is definitely inert. :)