Yes, if you had bought twenty years ago you would have made 1000x your money by now.
BUT......if you had bought in 1999 you would have had to suffer through a two year sell off which lost you 95% of your capital.
The moral of the story is....nothing goes up ad infinitum. You could EASILY see a 50%-60% FALL in $AMZN and it could STILL be in a very long term uptrend. The question is, do you want to sit through that or would you rather take your money now and buy at much lower levels in the quarters/years ahead?