I tried doing both for 2 months in parallel. One day I woke up and said "F*k this. I am done. Gotta quit". I then went to my boss and gave him the notice. I did calculate my risks as the business was just bringing in enough to keep me floating (with 2 kids and a wife). However on Day 1, my income was down by almost 75% (ouch, wifey was not quite happy but she supported)
Been 2 years since then and never been happier. It is tough, income is still less than I what I made in my cushy job but I will not give it up for that 9-5 bullshit. No more traffic to deal with (I hardly drive during rush hours now), no more commute (I work from where ever i want, mostly home office), I can take time off if I want or I could work on weekends if I want. The business runs 24-7 but I Don't have to.
Of course, not everyone is in a similar situation but we all have a path if you really want to do it. Bottomline is that you have to really really want this. It is almost like an addiction to do your own thing and not work in a shitty (Even if highly paid) 9-5 job. My job was so easy barring the shit commute. I could go in, talk to users all day, run projects, write some code and at the end of the day, I will get a big fat paycheck. People loved me at my job. I loved them back. Easy as hell. But I didn't want that anymore. I was not up to it anymore. I wanted to quit my "cushy" job.