But Mellanox is making niche equipment. You don't need an Infiniband interconnect if 10-Gig Ethernet will do the job. Only densely "coupled" problems, where the answer calculated on one core affects the answer calculated everywhere, need that kind of ultra-high-end interconnect. Your typical app scales very nicely across a bunch of servers connected with commodity networking.

This is more like a race car company not being as valuable as Toyota. Yes, the technology of the race car is unbelievable, but there are only a few thousand race cars in the whole world and there's a Toyota in every household.