Part of your evolution in poker is watching training videos and reading strategy forums. Another part is playing hands. I think the biggest part, though, is experimenting to see what playing style you are comfortable with and what works well.
As a poker player you need to be brutally honest with yourself. If you have a negative ROI over many games you are doing something wrong. You're not just running into coolers or taking bad beats. Over a big enough sample size there is something else happening which is preventing you from winning money.
No one person is inherently luckier than another person. Do some people run better in big spots? Sure. Look at Darvin Moon at the WSOP Final Table. Phil Ivey will never again in his lifetime get it in with AK vs AQ for tons of chips at the FT of the World Series Main Event.
But when you look at things on a grander scale, no one will do better flipping or in 70-30 spots than someone else if you both get into them hundreds of times. Math has no prejudice.
This is why it's so critical to be honest with yourself and to constantly try new things at the poker tables. Stop and think about big 3 bet pots you've gotten into – there will be some sort of trend with the actions taken and the results had. What are those trends? Do the chips usually get pushed in the opposite direction? Something is wrong, then.
If you're a losing player, try doing the exact opposite of whatever style you are currently playing. Then slowly make minor adjustments from there and strike a healthy balance for yourself. But in my opinion making an initial drastic adjustment is the way to go – like quitting smoking or another vice cold turkey. It just seems to go better for those folks than the ones who promise they will wean themselves away from things they want to stop doing.
So take the plunge, especially if you have expendable income. What have you got to lose if you're not already winning? Think about it.