I don't think it can be a source of main income unless you're trained in daytrading and TA. And with that, even TA experts say that crypto doesn't follow TA.
That said, I think daytrading crypto is gambling.
Bitcoin can't be a main source of income, because you're either hodling or selling for profit that one time. It's more like an investment that realizes.
I would not be a good financial advisor if I told people to make bitcoin their main income. They need a steady stream of income daily to make ends meet -- and you can't force the crypto market to give you that. On some days you're forced to hodl, and on other days you're forced to sell (if you know without a doubt that things will go down).
Produce bitcoin not only with daytrading, there are many other ways such as social media bounty, signature, and so on. I think bitcoin can be used as the main livelihood, as long as we really understand and smart take the opportunity. Because there are so many things we can do to get bitcoin. Side business is also needed when we already have enough capital to keep watch when the income from bitcoin is declining.