Investing should never be mandatory and should only be done with funds you can afford to lose. Especially for highly volatile and risky assets like cryptocurrencies. So I don't think it's a good idea to focus on a monthly plan if the amounts invested are substantial. People doing that should do it as a game of chance, without specific goals. If they win, they must be happy, but if they lose, it shouldn't affect them, they shouldn't have to care about it.
It is not mandatory. However, many people, even those who are not capable, try to invest their little money with the hope of having a better life for their family. However, if their investment fails, they will be disappointed and lose confidence in investing. This can lead to a negative impact on their future investment decisions.