First of all $400K is high for somebody with no money. But to make it COMPARABLE, let's say you are deciding between renting for $2,500/month or buying a $400K house. Let's say that in 5 years you want out:
Rent - $2500/month x 12 months x 5 years = $150,000 in rent (

)
Mortgage - $2500/month x 12 months x 5 years = $150,000 PITI (principal, interest, taxes, insurance)
Let's say you were in a fully amortizing 30 year loan of $400K, here's how your balance looks (courtesy of
LOAN AMORTIZATION SCHEDULE - Year By Year Display)
Year 1: $394,359.79
Year 2: $388,416.24
Year 3: $382,153.03
Year 4: $375,552.97
Year 5: $368,597.95
So even if your property value didn't change just based off the numbers alone you are saving $30K off the rip. And look at 10 years:
Year 6: $361,268.88
Year 7: $353,545.64
Year 8: $345,407.02
Year 9: $336,830.69
Year 10: $327,793.12
By year 10 the numbers are even more substantially different. You have $70K+ in equity off payments alone. And by year 10 you would have made $300K in rental payments (

). Again, this is assuming zero appreciation. Even after 5 years if you decided to move, you simply rent the property out and pay the difference between the rent and the mortgage. If you are making $300/week living paycheck to paycheck a $400K house is not for you, but if you are a professional of ANY sort the first thing you want to do is stop renting and start owning. Buy smart, don't overspend, and pay down as much of the principal as possible every month. This is the sure way to financial stability.