Considering the the economy, the value of homes, and the amount of foreclosures available to buy, I'd say that if you're in the position to buy a house now, do it!
It's the smart thing to do and you can wait to buy the M3 later.
I just bought a couple of foreclosed condos and renting them out right now for a good deal more than the mortgage payments. If anything, go buy a foreclosure, stay living with your parents, rent out the foreclosure purchase, and if you do it right, you can still afford the M3 on top of all that
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2021 A6 Allroad, 2020 SQ7, 2019 M5 Comp, 2011 GT3
past: A4, S4, X5 4.8is, SLK55, E60 M5, RS4, ML63, E92 M3, Q5, Touareg TDI, Escalade, SQ5, RS7, Velar FE, Q7