Poker is a game of skill which has a chance component.
There is tons of luck involved in poker games, including what types of bad and mediocre opponents sit down, what the comp policies are, and what your health is like (stamina is a huge part of poker, partially because it pays so god damned poorly).
These uncertainties do not go away in human lifespans.
But sit down and play 5 or 10 million hands online (that's under a decade of regular play, well within a human lifespan), or even considerably less than that, and luck becomes a rounding error. Mathematically. Incontrovertibly. Your long-term results in poker will reflect your skill level closely. And of course the rake plays a part as well, by turning poker into a negative-sum game instead of a zero-sum game, and dragging everybody's results slightly south of where they would have been otherwise.
But rake or no rake, there's very little "luck" in poker at depths of millions of hands, as you get in today's online games.
And even in the live game, where hand throughput is lower, luck is a small enough factor over the years that the same skilled players win consistently, and you can only win consistently by learning those skills.
Incorrect. In a game with no house, this may be true, but in a a game raking, it depends a lot on what sort of players sit down against you.
So if you want to put 'table selection' under skill, yes, I'll grant your point, but without judicious picking and choosing in that, poker can very much be a losing game just like most other casino games.
Look at the O8 games in Tunica for instance. Dead dead and deader because no one except people on oxygen tanks ever plays them.
It takes a lot of confluence of factors to beat the house drain on games (I'm talking in person games, not online games; online games are "merely" illegal, but otherwise you'll likely be fine in the longterm).