if they find a major bug in its security like a securirt hole people will lose trust and it will go to 0
I think bitcoin already quite perfect and before launching bitcoin would have done checking. no bugs in bitcoin for now. but when there is certainly that would be a serious problem for bitcoin
I think not, nowadays many bitcoin user complaints, for example a long confirmation, the cost of the higher fee and so on. I'm not sure bitcoin can lead for 5 years again, certainly there are coins that will replace the bitcoin.