Having a crush and constantly having crushes is good. It helps
you feel alive and give life meaning (not only of course, just one
of the ways to help give life meaning).
Having a crush is bad if you do not handle it well.
Not handling it well includes:
1. Imagining a long term outcome from short term crushes
2. Letting your short term crushes interfere with your long term
commitments
Crushes are fun and create lots of positive feelings in you as long
as you understand that they are fleeting and "for fun"; not for
long term relationships.