A lot of talk in here about grades, but if you're looking to maximize the likelihood of a card holding/building value, you should be looking at cards that are numbered so low that they don't need to be graded. You don't want a card that there are 500K of and that needs a PSA-10 to go from $15 to $200. You want a low numbered card (/1, /10, /70 etc...) that people are a lot less likely to grade. Look at topps dynasty auto rookie cards of great players - they're all number to /10 or below and nobody grades them. Topps heritage red ink rookie autos number to less than 75 etc... You're better off with an Ohtani or Whitt or Judge red ink rc auto or dynasty auto than junk that's only valuable because of the PSA-10 grade.
Also, look at population reports on PSA's site. There are like 25,000 base topps Soto rookies with a PSA-10. That's why the card went from like $400 to $70 orr whatever it is now.
But more importantly - Laika is right. Look at it as a hobby that you might possibly make a buck on if you're disciplined.
Don't invest in pitchers. They don't hold value unless its Maddux or Pedro or something. Don't sink thousands of dollars unto Eury Perez, Connor. Just buy a high end Ohtani or like Sandy Koufax or something.