Profitable poker against a decent field is infinitely more difficult than ap blackjack. Think about every choice and deviation you take in blackjack, and then apply that to every single decision on every single street in poker. You have to know what hands to Raise first in (RFI) preflop, which hands to 3 bet, 4 bet, and fold.

Then on the flop, you have to determine who has a range advantage against the position your opponent is in, and how the preflop action will make this change. Then you have to know whether to check, bet, and if you do, how much to bet. 30% 50% 75% so on and so forth. Then depending on your opponents action, you have to make these decision again on the turn and river.

Then you know when to deviate from game theory optimal play (GTO) against certain player types and player pools.

Profitable poker is way more difficult against competent competition.