From this vantage point it's comparable to taking a year off to travel (except 4X longer) or taking a couple of years off to volunteer. The question then becomes, can I afford it?
An interesting excercise is thinking about creative alternatives with similar costs. Say a parent was willing to give their 17-18 yr old child 100k in capital (maybe also help getting financed) + a 4 year stipend to start a business. Every cent must be reinvested. I'm not saying go start Microsoft. Maybe buy an ice cream franchise, mobile dog wash or double up & spring for an existing small business. Would they emerge 'more likely to succeed' at 22 then they would have otherwise?