A little feedback that might help if you decide to continue with domains:
- it seems all the parking revenue adds up to around 60-70$/year or enough to renew 6 domains. But you mentioned that most of the revenue were generated by a handful of names. So maybe you want to keep those.
- I looked through your names. So, overall, you don't have many bad names or incorrect names per se, but most are the names that are not suitable for a name of a company or a product/service. They might be ok for an info site, e.g., or a hobby site, but almost no one will pay $xxxx for that.
- Even after you nail getting names that can be desirable for business and sell for 4 figures and higher, combining both parking and selling doesn't work for most. The reason being that having a parking page distracts from selling the name itself and reduces the conversion drastically. And the landers are supposed to provide 40-60% of the sales leads. So you need to make sure your parking pays that and more to be worth to deal with.
- If you really want to do parking, test your names and keep with parking only those that pay for their renewals on their own. That way they are not a burden and occasional sale via a registrar path will be a nice bonus.