50 Cent came from nothing, and he has amassed a massive net worth by being a smart businessman. After he sold his stake in the Vitamin Water company for a reported $100 million dollars, he could purchase any car he wanted (via Auto Evolution).
50 Cent was always fond of fast cars and his Lamborghini Murciélago is perhaps the most notable example of this. The cars were one of the most popular sports cars of their era. He also owned a few other expensive sports cars.
The lead singer of Aerosmith has been a fixture in pop culture for decades. Many rock stars from the same era unmatched his net worth. This has enabled Tyler to get any vehicle he wanted (via GQ Magazine).
His Hennessey Venom GT Spider might be the most notable vehicle in his collection. The car was at one point the fastest in the world. Hennessey was known for building some of the fastest vehicles on the road.
Mayweather is one of the most successful boxers of all time. His net worth is more than Mike Tyson and many other famous boxers before him. Mayweather is not shy about flaunting his wealth around either (via Art of Gears).
His car collection is also reflective of that fact, as Mayweather has more than a few expensive cars to choose from. His Koenigsegg CCXR Trevita is one of the fastest cars in the world. The hand-built design is unrivaled, and the engine is tuned to perfection.