Being a flipper can be quite lucrative if you know what you’re doing but the number one risk is (in my opinion, at least) letting time go by without building your very own portfolio of “keepers” or in other words, not having any long-term domain investments whatsoever.
Focusing on the present (making money today) is great and everything but every once in a while, deciding that a domain is a keeper rather than something you’re willing to flip might be a good idea. That way, you’ll gradually build your very own portfolio of domains that you consider have long-term potential.
Otherwise, you might end up taking a step back a few years from now and saying something along the lines of:
“I’ve been in the domain business for several years, what do I have to show for it?”
Deciding to keep domains every now and then isn’t a good idea just so you have “something to show for it” after several years in the domaining industry. First and foremost, it’s a rational investment strategy which complements domain flipping.
You don’t have to “pick a side” by deciding to only be a flipper or to only be a long-term investor. Again, these two strategies complement each other.
How many domains should you decide to keep?
That’s entirely up to you.
The more confidence you have in the appreciation potential of domains, the more aggressive you can be in that respect. Think of it as your domaining nest egg