To sell them, It still happens. You just stay real quiet so when you get it to 10th Dan and sell it, whatever jackass bought it can be whoever and no-one will notice the change.
As it is I believe there is a win limit, and if memory serves it is 100 wins in a day. So if you can get 100 wins in a day, that's nuts! You're either cheating or need to get a job.
That's what we call farming. It's long term and kinda hard work. If you do it the right way, you are an exceptionally skilled and dedicated. Some rather cheat and 'lose to themselves'.
I can not provide any documentation on the win limit. I can not provide any proof of it. Still it's an idea I support. It balances the Toriconomy and raises the value of TC. Which means items get cheaper.