It's VERY safe. Try starting a restaurant. You have to borrow money, you need to handle staffing, fire problems, etc. That's a risky business. A web business, if it fails, you lose nothing.
We businesses are really very low risk business. Mostly, in case of failure, you just lose some time.
Hmmm...I understand what you're saying, but you seem to be presenting a false dichotomy where the only two options are starting a web company or a restaurant. For the vast majority of people with kids, the "safe" option is getting a good job that pays well and offers good benefits.
It's also a bit disingenuous to say that if your web business fails, you lose nothing. Perhaps that's true for a single guy who is starting a company with some friends, but for the average married founder w/kids, there is a significant investment that will need to made in the form of time spent on their startup, as well as mental and psychological energy. Not to mention any cash investment, and the lost income that could have been earned with the time spent on the startup. If you fail, there is a cost.