When mills were $5 a pop 50M could buy you a Blue, White and Green Party Hat or even the best gear available in the game with plenty left to spend. That's $250 in a time period of the game where your wealth actually carried a certain value. Compare that to today where a Blue Party hat will set...
That wasn't due to botting. That was because at that time there were few contributors of cash in to the game outside of monster drops. That all changed when RS2 was launched with bank notes which introduced mass-alching.