I've played poker since I was a teenager. Lifetime, I'm up in poker by quite a bit, but decades later, I'm still learning and I taken plenty of loses along the way. The rest of my post is based upon No Limit Hold'em as that's what you mentioned in your post.
Here's what I've learned: You can make decent money, but only if you're really disciplined. You need to be able to calculate pot odds and hand odds quickly and not make very many mistakes at all, preferable none and that's hard to do. You can't just go chasing down river cards all the time and you can't bluff your way out of every hand either. You need to know the odds, you need to have a range on what the other players in the hand are likely holding based upon their actions (are they betting?, raising? calling? checking? why? are they slow playing a good hand? are they bluffing? are they on a draw?). Only by playing thousands and thousands of hands will you really start to understand the intricacies of the game and the ways to exploit them.
The other thing you'll quickly learn and others poker players will mention this as well, is the fact that it is a "grind" to make money at poker. Variance is a bitch and sometimes it doesn't matter that the odds are overwhelmingly in your favor, you lose anyways. You have to play (and be on top of your game) for extended periods (not necessarily at one time, but overall) for the odds to work. The waves of up and down in poker can be brutal at times. Sometimes it feels like you just can't lose and you get the hole cards and flops you're looking for. Other times, you have hands with good odds of winning, yet you're consistently beaten on the turn or river. You need to play long term for those variances to work out and that only works if you're playing the correct odds in your hands.
You're correct that the rake is also a bitch and often hard to beat, even for above average players. I actually play sit-in-go style tournaments mostly or smaller tournaments, I rarely play cash games because of the rake. You have to strategize differently in a tournament than you do in cash games, but I've found these smaller tournaments to be my sweet spot so to speak and that's what I usually play and win the most often.
I tried playing online for a month to see if it was a way I could make a living (5 smaller tournaments each day) and actually was up quite a bit at the end of the month, but it drained my love for the game playing that much.
Start out just playing for fun, then read a book or two about strategies, then go back to the tables and apply some of the strategies - this is what it will take to become successful - doing this, then doing it again, then again...