I don't think there are those many people who suddenly leave their jobs to solely concentrate on Bitcoin. They might turn to it when out of a job and struggling to find a suitable, stable one that earns them a decent salary.
Of course it depends on where you live but the in current economy it's quite hard to have a good, well paying job so if you happen to have one, stick to it. You can still concentrate on Bitcoin in your spare time. It's never so immediate to start something and be profitable right away. Usually it requires a lot of work and time before you can break even. Once you're up and running and making more from this than your current job, that's when you can resign.
Besides, it's better to have a steady source of income that you can invest and that could later become a source of passive income.
When you go to telegram or in Slack, you will see how many people from first world country that do trading full time. They think that trading is much better than having a day job because you get to stay in your house and you have the time for yourself. I think so too. These people didn't wake up one day and decided they are going to trade. They have been trading already when they still have day jobs and just decided that they are good enough to trade for a living.
There's a transition going on. First, day job 100%. Then trading comes in. You trade whenever at your spare time. Then at one point you're doing well with trading that you just find that you're wasting time with your day job or that your day job is getting of the way. You then do trading 100%.
Personally, I wouldn't be so surprised if somebody here claim that he's been trading for a long time and he doesn't have any day job even when he live in a really good economy.
I do believe having a multiple line of income is reassuring, as grand as the prospect of bitcoin is, it still has its risk plus our regular job provides stability. I would rather do bitcoin as alternative bank roller, just as stated in the numerous previous post, there would be a transition from your day job to working bitcoin fully. And again you have the folks who are without regular jobs to start with or low paying jobs or underpaid jobs who have the luxury of time in their hands yeah bitcoin would be a way to go if they can get started.