While you're on 90%, your mind will tell. Go grinding that shit, you will get bonus money from the rank up. Then, you losing more money than the bonus rank up you're get ~XD. I still can't believe.
I cant deny that, I felt the same when I was on 80-90% to the next level. There was a whisper in my ears that suggest me to start wager more to reach the next level. Luckily I was not tempted as I did a calculation first to make sure that I wont lose more than the possible leveling up reward. I started to push myself to wager more when it was around 5% remaining to rank up.