On topic:
http://v.cdn.cad-comic.com/comics/cad-20120305-20729.png

Please don't tell me that people didn't know this already?

The companion cube as a console would be awesome. And I don't even like Portal...

Well, he was rich before Valve even existed as a company.

If someone managed to blow up all the major Steam data centres (or wherever there main servers etc are), he would be worth squat.

Half-Life 2 Episode 3 Kickstarter, anyone?

Offsite backups + using data centres at other locations would mean that sevice should even is such case be back in a few days(or less).

There really isn't much (most likely any) difference between the shares that he owns and those of other shareholders for the purposes of the valuation of the company. They will all have been issued for at least nominal value initially, but they will all be of the same value right now (unless they were issued at a premium, but once again, that makes no difference as far as the value of the company goes).

Which still doesn't mean he did anything good or praiseworthy for PC Gaming.

Good for Valve, they deserve it. Great company (mostly). I hope those steambox rumors are true and we will finally get some awesome standardised HTPC.

I'm sure he has a very nice nest egg holed up for himself.

No, there is a massive difference. They are assigned the same theoretical value, but in practice it doesn't work like that. If a random shareholder wants to dump shares, they can do so pretty much no questions asked. If Gabe tried to unload all his shares, there would be massive questions asked about the long term viability of the company.

It's a well documented issue that occurs in companies that are build behind one or two key figures. I'm not certain how much it applies in the case of valve, but he would be unlikely to get $1.5 billion for his shares if he tried to dump them.

Sorry to say, but you're incorrect. Valve is a private company, they are not listed on a stock exchange. This put immense constraints on how, when and to whom shares are and can be disposed of. It is 99.9% certain that there is a right of pre-emption within the shareholder agreement, as well as terms as to how shareholders can dispose of their shares. The share capital is rather stable and allotting new shares and buying back old ones is a rather arduous process. Shareholders cannot just simply dispose of their shares like they can do with those of a listed company.

And obviously change of control is a relevant issue as far as share transactions go, but this doesn't necessarily have the effect of reducing the value of the company. If, say, Steve Ballmer or Bill Gates offered to purchase the majority shareholding from Gabe then this would have the likely effect of skyrocketing the value of the shares - he could get double of their current value for them. The company is a private one and thereby not permitted by law to offer its shares to the public at large. The relevant audience for purchasing Gabe's shareholding is rather small and would most likely have the effect of increasing the share value of the company and not decreasing it.

It's always obviously possible to reduce the share price by entering into stupid transactions but a prudent business like Gabe is unlikely to do that. He can get more than his money's worth for his shares if he wanted to.

Do you know does our fiat money is only backed by "trust" and no value itself? ;)