Its not that bad - just remember its only a game.
Played for 3 hours online this afternoon in online career and probably met 3 or 4 people who were deliberately knocking people off, everyone one else was at least trying to race, but many of them just werent very good. After a while you start to learn where its safe to overtake them and which players to take out before they do it to you.
Mind you though, I will never handbrake turn over a finish line again. I did it today on Majestys Pleasure and came to a stop aboout a foot off the line. Didnt realise att first then watched everyone from 3rd to 7th pass me lol. Cost me a drop from 9455 to 10100ish