It was a long time ago, and I can't find anything to corroborate this on internet searches, but:
Didn't Borland attempt to charge for the use of a c runtime module? They attempted to profit from software developed using their c compiler. So, not only would they make money selling the compiler, but anyone that used programs written with their compiler would have to pay also.
Somewhere around that time, they lost the whole c compiler market, I think.