So far, the only method I know at the moment is "trading" and that's when BASEBALL CARD prices go down, I purchase a few BASEBALL CARDS and sell it back when the prices are profitably higher than the amount that I purchased it historically.
Also, I've checked the marketplace and I've seen lots of digital goods being sold such as those digital accounts which can be paid in BASEBALL CARDS.
Now my question is, are there more things that could result into creation of money from BASEBALL CARDS and from this forum?
I replaced words in your post. I hope my point is clear.
Honestly, if you want a steady legitimate source of income, my recommendation is to get a steady legitimate job.