I imagine my feelings about Venmo reflect a lot of peoples':
Basically it was the first way to send money on mobile phones that wasn't miserable or charged fees so everyone started using it. By the time PayPal owned it it was already popular.
Everyone wanted to easily send money for at least, like, 10 years before that. It was the first mainstream option and it still felt really late. (PayPal already existed but was... disliked. I think because of lots of horror stories about customer service, and maybe not having a convenient app interface, or requiring a bank account connection?)
The competitors are all equivalent now (FB, Google, whatever), but I would never embrace using a FB or Google product exclusively so Venmo feels like a 'neutral third-party option' , at least to an extent, which we can use as the 'default' payments app.
The Bank's versions (Zelle, etc) are way too coupled to banks and too big-corporation to be excited about.
If there was, say, a startup that did exactly the same thing as Venmo but wasn't affiliated with a big company (PayPal), I think everyone would happily use it. If it was, like, a B-corp or non-profit that gives proceeds to charity, I think everyone would jump ship instantly.
Basically I don't care at all about Venmo's social features, I just want to send money and prefer not to support a big corporation or give more data to FB or Google. I bet lots of people are of similar mind.