Most I've ever reached was about 4.5M+. I just want enough money to get the bigtime autos. Then too, I've done the DTM a few times because I'm not wasting my time with the Nürburgring Nordschleife several different times just to rack up finances. Easy and quick money can be had with the Costa di Amalfi rally. You can quickly make 250K by winning both races (don't forget to clear scores first) and selling the radical rally raid car. It's a good car for rallies, but be sure to keep an extra if you don't already have the RSV(?) Rally Raid Car.
I've basically given up on trying to compete with others. Like when I did my high-speed deal, I said I did about 270 or something, then I've seen these 300 mph deals. Most I've ever done was 270+, and it was about the fastest you've gone, not who has the highest speed. So, when I had a lot of money, I either modified cars or bought cars. I'd love to get 4.5M to get the 2003 Pescarolo prototype. I already have the 2004 one, so one more wouldn't hurt, right? Anyhow, I haven't reached nine figures yet. In fact, I may never!