I started my guy as a smuggler to get rich quick type of style after that I got bored and started to meddle into some political affairs now I have my own single star system empire but I'm wondering

Can I not ever get my own battleship?

I mean its hard enough trying to destroy a single battle group with a freaking cruiser.

Will I ever get the skills needed to get a battleship?

Or am I stuck being a lowly smuggler pirate king with just a measly cruiser?

Correct. The only way to get a battleship in the game is to capture one. I had a battleship long before I started my own empire.

Man that sucks

Smugglers are geared more for blockade running and trading, also they may work better without signing on to a factions military so no ports are closed to them due to war. Also the Amnesty skill is a MUST or you may spend half your game waiting out your wanted levels if you have a string of bad luck
A smuggler/pirates endgame is to make and direct their own empires. Traders are to bankroll their factions war efforts and "buy" victory via war bonds. Fighters are about getting that battle ship and taking down whole systems yourself.

This game is kind of like Pirates! were winning the war is more of a meta goal, its more about how you build your reputation and wealth, thus the option allowing you to retire at any bar and leaving your objectives to you