Having one income source is better in some cases as I have seen that as more you are earning your expenses will be increasing more. There are numerous individuals who are living their lives only in a single source of income and their life is better than those who are earning lots of money.
Some people have less income but they know how to manage their finances and they know how to save money so they are happy with their lower salary. But still if someone wants to earn money beside their salary then crypto is the best field through which one can earn and that earning amount can then use for investment.
There is going to be a financial level you will reach, the money you used to think is large is actually little because then you were living below that level. If in a year you probably earn $50k and you don't have a car and girlfriend, you will always see $100k/annum as a big deal but as soon as you start earning more than that $100k and above, everything about you change, that's when yiu start looking into big things, thats when you even consider having a ride and because of the maintaining culture, you will spend more and 100k become a usual money in your eye.
Having different husle helps you not to depend on a single source because I have learn that in this life, nothing is guaranteed. If you have a single husle and that husle run into a problem, you will feel it even if you have savings, in 6 months you will go down but if you have two husle, you wouldn't feel much pressue but the effect will be there for sure.