They won't do it themselves, they'll pay for it. People already do it with brand new ICE cars, they get a performance package from a third party.
Also in 10 years, that $150000 Benz will be a $15000 Benz and owned by someone a fair bit younger than the original owner, probably. Much more likely to get the controller flashed for additional power at that point.
I heard of a guy who tuned his already 500 hp Benz to get it over 600 (now he is under arrest in my country for street racing).
They also do this a lot with BMWs, e.g. the 318i and 320i engine is the same, so if you just change/hack some software setting on the 318i, you can get more hp out of the same car.
But these are of course the minority of people, and mostly targeting sport cars, not luxury sedans.