I think one difference between Dropbox and Spotify and Twitter and Snap is that Dropbox and Spotify sell a desirable, useful product to end users.

In other words, there's a clear function being offered and a clear path to giving them money in exchange for that function.

While both Twitter and Snap are functional, their only real offering is a slight twist on you general social network, and their only way to make money is by advertising to their vast consumer base.

As an investor I'd be far more interested in the revenue streams provided by Dropbox and Spotify.