Ok.
I thought about this a little bit. You are trying to say that yishivish equals tzadik and the more you got the bigger tzadik you are. Therefore you ask “How can it be bad to be the biggest tzaddik? More Olam Haba. Yay!”
The problem here is the premise. Yeshivish does not equal Tzaddik.
Yeshivish equals appearance of Tzaddik. There is no problem with appearance of tzaddik if the appearance matches the level you are on.
There are many problems related to this which may include but are not limited to: Sheker to yourself, sheker to others, gaavah, and the problems and sub-problems contained therein.