One analyst's view of a noted drop in VC activity:
In general, VCs are doubling down on “winner take all” leaders....
Overall we believe 2012-16 was a bubble in early-stage funding driven by the fundamental platform shift to mobile. ...Arguably, post implosion, early-stage VCs have become more “rational” and we are unlikely to see the “spray and pray” approach that dominated a few short years ago.
https://techcrunch.com/2017/11/30/theres-an-implosion-of-early-stage-vc-funding-and-no-ones-talking-about-it/The robotic vacuum market is also more crowded than it was a few years ago with more major brands participating and increased competition from China. When Neato Robotics started a dozen years ago, iRobot was virtually the only major offering, and Neato has never managed to take more than a small part of their share of the market.
I am reminded of how there could be a lot of software startups in PC's until the big firms like Microsoft take over the business -- sometimes by buying the innovative firms, sometimes doing it themselves.
When automobiles were first invented, there were numerous small brands, later consolidated into General Motors and the other giants as the product became mass produced.
A lot of appliance brands offer some robotic vacuums, but you don't hear much about them, with nothing especially exciting in terms of innovation.