The sports card industry (specifically baseball cards) crashed in 1994. Fantasy sports existed as early as the 60's, but really caught public attention around 1995. That timing is not coincident.
In both hobbies, fans get to have surrogate ownership of players, and the market value of those surrogates goes up or down with the performance of those players. At the casual level, being in a fantasy league is just a more publicly acceptable way to collect and play with cards. At the serious level, fantasy is a more viable, faster way to make a profit with your expertise than cards were.
In short, fantasy is just trading cards for grown ups.
But what if physical cards let you draft players?