When I got my Novice license (1965), I could not afford QSL cards or the postage to send them anywhere. Cards only cost about $5 or $10 back then, but gasoline was only $0.23 a gallon. And gasoline was more important to me. Once I could afford cards and postage, life was too busy and I could not get into the habit.
I never had any need for QSL cards. I was never a contester, chased rare DX, or chased awards, so there was no real reason to have them. Rare DX chasing can get quite expensive. They get a flood of requests for QSL cards so some of them require $2 or $3 to receive a QSL. That can add up pretty quickly.
It's like anything else in this "hobby", if you like to send and receive QSL cards, that's fine. Do it. If you don't, that's fine too. The same is true with log books. While most hams keep a log (electronic or paper), there is no requirement to have one. Personally, I only keep a paper log.