So would say about half the time you get cron stone from doing Dark Rifts and now can not sell them. So all you do is lose silver by doing them and get nothing in return. Yes you might get something worth silver but a lot of time not that much and that does not off set the lose from Cron Stone.

Just don't do them then.

Problem solved.

collect  crons for 2 times a year hammer giveaway, fail and make it you bi-annual ritual, like me XD

Use your crons on T9 attempts.  You don't need to use them for enhancing.  Your horse doesn't go poof when you fail and it doesn't downgrade.  

You can always find some things to enhance with them. 

Honestly, just save them. I'm sure you can find one storage/inventory space somewhere. Personally I think anyone that sells/deletes Cron Stones is a little short-sighted. One day you may want them, and on that day the many thousands you have stored away you will be very thankful for. And if that day never comes, well you've only taken up 1 space somewhere. There really is no downside to keeping them.