The Roots are one of those groups where once you scratch the surface you soon realize they have been so so so influential in the world of music. They have guided, produced, and assisted a crazy amount of now renown musicians including Erykah Badu, Common, D'Angelo (Voodoo won a Grammy), Jay-Z, Amy Winehouse, John Legend, Elvis Costello, Slum Village, etc. They have also worked on films and broadway shows, most notably 'Hamilton' (where The Roots are credited as producers). This is all before we even mention their own albums.
They have released 11 studio albums (9 of which ranked within the top 5 US R&B Charts, and 7 breaking the top 20 US Charts) 2EP's, and 3 collaborative albums (2 breaking the top 20 US Charts). They have 3 Grammy's (not including the Grammy won for Hamilton) plus countless other awards. Their live shows are constantly ranked as being amongst the best in the world, and the critical reviews match this claim. Its difficult to state their net worth from music alone, but Black Thought has a net value of $12Million and Questlove had $16Million. Its more than likely that a considerable chunk of this stems from their albums. I would also add that they are one of those groups where you may struggle to name a song by them, but they actually have a load of instantly recognizable songs.
I completely agree with you that a lot of people will only know them as 'Jimmy Fallon's House Band', but the reason they were offered that role is BECAUSE of their already stellar career. In fact, when first approaching them with the offe, Fallon completely expected to be turned down by them, and it wasn't until Questlove turned the corner to see Fallon and the rest of the Roots messing around (they were on the floor making a human pyramid) that they agreed to be part of it (they thought it would be a good platform to remove the pressures of their other work and just play around).
This was a actually a fun exercise