I'm preparing for the college entrance exam to go to college, so I can't make money from working. I get about $100 of allowance from my father every month. I use all of them to buy bitcoin because I can use father's credit card for expenses such as food, clothes. I can buy Bitcoin on a satoshi basis every month, but when I see people buying Bitcoin basis on the internet, I feel like I'm too behind myself. Maybe they have a much higher income than me because they have a job. I think I can only invest $100 a month for the next year or two, would that be enough? I am worried about missing big bull market with halving and etf approval.
Buying bitcoin with $100 monthly is already a good amount for a student like you. You don't have to invest bigger than what you can afford to lose, as you are still dependent to your father and is still not making a stable amount of income. Invest on your own risk.
But I also have this question in mind if you are going to invest all your allowance, then where will you get the money that will be used for unexpected expenses? You have to reserve funds like for your emergency funds so that you will have something to spend in times of emergency cases. Investing is good, but always prioritize saving for emergency funds and just only decide to invest when you have spare money available.
That is what I was thinking as well, investing all the money that you receive each month is not possible, even those that have a job and do not have many expenses still need to reserve some of that money to cover their daily necessities and any unexpected expenses that may appear, so a more sensible amount will be to invest 50 dollars per month, which is only half of what the OP was planning, but this is an amount that could actually be sustained over a long period of time.