I'd support you in everything you said apart from the part where you said one can become a Bitcoin miner. The reason is that individual mining is not profitable anymore unless someone is ultra-rich and can afford to create a mining farm with a lot of mining equipment and for that, they will need to make sure they are getting electricity at a cheap rate so that the coins they might mine shouldn't go in maintenance of the mining farm alone.
You are right about trading having another source of income when they are trading, especially when they are new to it. Someone experienced might be able to become a full-time trader because their mind becomes mature after some point and they can make sane and critical decisions even under a lot of pressure.
I think even someone who is experienced, could still realize the benefit of having a source of income that is not trading. That doesn't mean that a veteran who does very well profit should go out and find a job, if they are happy with the amount of income they are making, they shouldn't really end up working for someone else.
But they could have a passive income, put some money at 8% bonds, or just do staking at crypto, or whatever else, dividends from some stocks maybe, I do not care. In the end, there should be some source of income coming your way even when you are not trading, and if you do that, then you live off that income, and then your capital at trading will not be touched and will only be used for trading and not living.