Um, maybe you haven't been around because your account is old enough as a hero member i can't say you are new to bitcoin! everyone knows the reason already. it is not really something weird.

the scaling debate has ended and all the uncertainty went out of the window when SegWit reached the 100% support. before that, everyone was either scared, uncertain or both. so they were hesitant to invest in bitcoin. and so far bitcoin is still the same decentralized cryptocurrency that nobody can control and also has a very small and limited total supply.

and now all those people are coming back, knowing that issues are solved and there is only upwards to go.