"you can invest your savings. If you ain´t got any, you ain´t gonna invest". (I admit you could argue that you can borrow but still nobody ain´t lending ya if you ain´t gonna givvet baksh).
Borrowing for investing is usually a bad decision.
Normally yes! But not in times where you hardly have to pay interest for borrowing money. Suppose you borrow money for less than 1% per year. The stock market has brought an average return of 7-8% in the last years (blue chips). After taxes and interest, that would be about 5% profit. Of course you have a certain risk, but you always have that when investing, even with equity.
But I would not invest borrowed money in crypto as the risk is much much higher.