Well for me, reasons to invest in bitcoin is
1. Its is now the main thing in this generation, in the world of cryptocurreny this is pretty much the thing that will make you richer and earn more money.
2. Bitcoin, attracts other investors or companies etc to build up their own coin in the market. Therefore making you an option to which cryptocurreny will you invest with, just like ethereum etc.
3. Bitcoin will not let you down, as long as you have the right mind and right move at all times it would make you earn more than what you invest in for.