Is worth it?

yes, it's worth it, your karma will increase drastically =)

i was asking to know if in the giveaways with a minimum 50$ of contrib. value there are more chances to win.

Spend $50 on sale games and give them all. Then you may notice sometimes there are giveaways with only X hundreds of entrants. X depends on the days the giveaway lasts. Just check it with your eyes, nothing impeds you to be observative. You can also switch open to closed giveaways.
But probably is better to spend that money on your desired games and not in trying to win random games and forget this site! This isn't a place to "invest in".

go for 50.01

Don't make giveaways just to gain CV. Make them if you feel like sharing. If you don't, save that money for the game you want.

Your wins on profile looks sad:((

ok, i feel to give some thing, i won 12 games till now.
i made this Giveaway

You need pretty high CV for it to start to be noticeable. Even $100 CV has hundreds of entrants. Maybe at $500+ you start to see a distinct difference but as it's been said before; give what you want to give away, don't try and "invest" in the site hoping to win it all back.

Perhaps you have won 3 times the same game?

i do not want to win the same game twice, but if i enter in many giveaways that has the same game, i have more chances to win one giveaway.But if i win 2 it isn`t my fault. I expected to win 0, but winned 3.

OK, thx to all once again!