Do you know why most player does not play with pirates ? I find it quite fun ..
End of davidoux's quote
Its random, arbitrary and certain to bite you when you can least afford it. The exact amount of time you have to place bounty is random so no one can "play" the system with certainty, but just 250 credits can make the difference between getting raided when your main fleet is already getting hammered by a real enemy. Ironically since you probably have your full attention on the attacking forces in this case, you're also most vulnerable in a bidding war as you'll be most distracted. As long one player has more bounty than you, it doesn't matter how big it is, in theory you could have a huge bounty on you the entire game, and never get a pirate raid sent at you. Most people say they would prefer pirates that wouldn't follow a set schedule and just attack whenever bounties get high enough (you can sort of do this with pirate missions though).
On the other end of the spectrum, for the good players at best its just a mild inconvenience to deal with pirates, at worst its free XP for their caps or worse titan. This means with an all pro game, if pirates were left on no one would place any bounties (and they certainly have more pressing things to spend money on), and they might actually want to be the target. Since if all players have equal bounty the pirates attack randomly, in a perverse way its randomly helping certain players, and the pros only want enough randomness to keep the game interesting, mainly in map positions. Anything else they hate, since it interferes with testing their skills against each other.
In short, pirates have always been to hard for new players, discouraging them right after the tutorial, and not hard enough for the best of players. The devs have tried making them both harder and easier than they are now, but this just shifts people from one category to another, its just something you can never please everyone with. So most people turn them off.
What about Kol ? In this game, I need to invade one more planet wihch is heavily defended, because of my flourishing economy I took time to build a gigantic fleet (lvl 10 titan, 5 Kol leveled to 3, countless frigates, strike craft, corvettes, repair ships ...) even with this overwhelming fleet My kols are wiped out in a few minutes (I'll try to post a record/screenshots too). I don't really understand how this is possible
End of davidoux's quote
The Kol is actually the laughing stock of the TEC capitalship roster. It's the signature ship of Sins (people who got the collector edition of Sins will get a model of it), but its been woefully weak for years. Its main problem is its a huge antimatter hog. It never has enough to use all of its abilities at once, and even using just one it will tend to run out before other caps until you get it to level 6 and its ultimate, finest hour. This is a decent ability, and if you ever do build a Kol its to get Flak Burst, to try and deal with tons of enemy strikecraft late game. By then though bomber swarms usually have no trouble dealing with a Kol, so its very much a last ditch options.
Its other two abilities, Gauss Rail Gun (GRG) and Adaptive Force Field, are seriously weak, other abilities outclass them in every way, and they only affect one target, making them near useless late game, and early game the Sova carrier is better than the Kol (and probably every other cap) in every way save perhaps endurance, but its a carrier and doesn't need to be in close.
Now it does combo nicely with the Dunov battlecruiser's ultimate, which reduces antimatter costs, and if you also have finest hour the Kol can fire enough GRGs to actually make a difference. But you'd as much damage to an unlimited number of targets with the Marza's missile barrage, and one level 6 capitalship is far easier to get than two. And for the record if you really need a tough to destroy tank, the Corsev is a much better choice as its defensive ability is passive, it can capture enemy ships and do Area of Effect damage (AoE).
As for what actually took you out, its hard to say without even knowing what race you're playing against, but there are a handful of special abilities that are quite capable of doing that, especially if you aren't aware what units have them and how to avoid them. Its also possible you overestimated your strength or underestimated theirs, new players tend to do that. It does no good to build an invincible fleet if you can't recognize a death trap when you see it.