Are Banks injecting unlimited FIAT to control limited cryptocurrencies Is the sign of a next financial crisis ?
haha, if they attack like this we will soon replace their system with bitcoin
but no, you are overthinking things. bitcoin is growing because as you said Japan legalized it and that led to a massive increase in Japanese volume rushing to buy bitcoin and the rest of the world has been reacting to the news too. they are also buying bitcoin and a couple of other countries are taking the same legalizing path.
and as for altcoins, this happens almost every year when they get pumped and take a lot of money from bitcoin invesstors not anybody from outside, and go up a lot into bubbles. and then they pop and die slowly until next pump round.