All in is never good. Only if you lik eto gamble hard. High risk => high reward
True. You can't say bitcoin will rise %100 high reward = high risk it is like a physics rule.
When it comes to bitcoin you really cannot say never,because it has increased hundred fold many times ,since i am active in bitcoin trading and sure it is a high risk investment,one thing i did not understand here is that,which physics rule are you talking about,since i am not familiar with it.
Still no mechanism is there through which we can find out the actually number of bitcoin users, in fact most of the bitcoin users have more than one wallets therefore we even cannot get any idea from there, we can just do roughly estimate and that is from the increasing price of bitcoin, we can only conclude that the users of bitcoin are increasing because of the increasing price of bitcoin which is increasing due to high demand of bitcoin.