Not sure is this will change anything or just reinforce your thoughts, but from a basketball perspective, I would say the first question you need to ask is "what do I actually want out of this?".
If it is to collect and have fun the answer is going to be very different than if it is to find something with "potential upside dollar wise" (ie invest.)
If it's the fun side, then this differs for everyone and only you know the answer to what you enjoy.
If it is potential dollar upside than, in my experience as a non-investor, if you want safety and the most likely — though not guaranteed — to increase in value the answer is simply Michael Jordan. it wont be cheap, especially if you are chasing anything beyond base but it will be pretty safe.
Kobe Bryant, pre-80s rookie cards for the main HOF players are also relatively safe.
If you want high risk then you go modern, but that is a crap shoot to me. Rookie cards of young stars are theoretically what you want, but the hype is so much and the price so high for early draft picks immediately that you are buying the peak almost instantly. If injury, suspension, just plain under-performing expectations (and in some cases it is almost impossible not to under-perform) strikes then returning value is extremely hard.
I would try to "buy the dip" on players we know are good but for some reason have dropped in popularity. As I'm not in the hobby for dollars and cents I don't follow prices closely but I imagine Doncic values took a hit last season when Dallas cratered, but it was hard to see missing the playoffs as the yearly expectation for them. Same with Anthony Davis a few years ago.
Someone mentioned not chasing second round picks — I'd almost go the opposite. Anyone outside the lottery/top 10 generally has little hype and low card values. Sure most of them will miss but if you could get say 50 players for less than 40c a card on average that's $20 per year's rookie class. If you go back through the last few drafts and sort by win shares you get:
2020: Haliburton (pick 12), Maxey (21), Bane (30), Quickly (25)
2019: Morant (2), Gafford (38), Clarke (21), Claxton (31)
2018: Doncic (3), Gilgeous-Alexander (11), Young (5), Bridges (10)
2017: Tatum (3), Allen (22), Adebayo (14), Mitchell (13)
2016: Sabonis (11), Siakam (27), Poeltl (9), Zubac (32)
I have no idea what that proves and win share accumulation certainly doesn't equal hobby $$, but it is interesting that there isn't a single No 1 pick in those 20 players. Fifteen of them were pick 10 or later and nine were outside the top 20 picks.
You probably don't get "rich" doing this unless you hit a Jokic (41 in 2014) or Antetokounmpo (15, 2013) and you likely still loose money but I would feel better about it than say having paid the price for Williamson, SImmons or Ayton RCs at the peak of their hype.