Penis envy is a strange thing.
There’s the “I don’t have one of those” type of envy. Be careful of this one. If you’ve never had “one of those” it probably means you don’t really understand all of the consequences ownership comes with. At the very least you’ll probably also have to buy some other specialized stuff to store/carry/clean it correctly. And even if you know what it does, that doesn’t mean you know how to use it to best effect…
And then there’s the “embarrassed at the public shower” type of envy. The “mine’s not big enough” or “his is bigger” thing. It’s not all about size.
But, there are some good reasons for penis envy. If you want a long term relationship, then you probably need something with the ability to focus on only one thing. And it needs the ability to maintain that focus in tough situation.