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If I deposit $100 or $120 worth of bitcoins per month from here, how much will it benefit me? Is it right for me to invest more $ in Bitcoin than this? And should I invest the whole money in Bitcoin?
If you invest $100 every month, it means that you will have $1200 (in BTC) in one year, and if the price of BTC increases by 100%, it means that you will earn exactly as much as you invested (minus tax if you have to pay it). Considering that you are asking whether you should go
"all in", then you probably don't know about the rule that you invest only as much as you are ready to lose.
In addition to the fact that the price of BTC is volatile, take into account other risks such as hacking, phishing, physical robbery and natural disasters. All of the above can result in you losing your investment in the blink of an eye.