100% true one has to put in some amount of study to be successful and be a winning player. How much will depend on the stakes on plays and how high one wants to try and play or reach.
With that said even 2024 one doesn't need to spend a dime on courses/books when starting out. This forum has a 30 day course take it. The internet has endless amounts of good info and knowledge and that is all you need to be a winning player at micro/low stakes.
What one should spend money on right off the bat is a HUD and I don't even care if your site allows you to use it live at the table or not doesn't matter. A HUD is a great tool when it comes to being able to study and do hand reviews. If your site allows it also helps rec/hobby players be able to multi-table more easily. I prefer Poker Tracker(PT4).
One also needs to study/work on and get decent at the following things:
bankroll management, mental toughness/tilt control and patience. These 3-4 things are the keys to actually being a winner long term. If you can't get at least okish-decent at these 3-4 things......then no matter how good at poker table you are it won't matter long term. Long term you can't even be a micro/low stakes winning player with doing them 3-4 things decently. You could be the best player in the world at the tables doesn't matter if you can't manage your money, are mentally weak and have tilt issues.
Cheers!!!