If (and I do mean if) she actually enjoyed playing softball after all her father's pressure, she probably would have been able to play it much longer without the intense focus that eventually blew out her knew.
I think your original argument was valid (make smart investments (educational RSPs) rather than personally motivated investments (softball). However, I would have backed it up by coming up with number of softball players/softball scholarships, expected return on RSPs over 10 years etc not anecdotal evidence like "If she actually enjoyed playing..."
