Most hosts that sell 100TB from Evoswitch seem to be resellers of Leaseweb. Very few own their hardware.
Those that own their hardware, very likely have one or more 10 gigabit uplinks. This requires significant investments as well as the knowledge to configure such switches.
But the fact is, that all 'cheap' 100TB deals out there are based on overselling and have various restrictions (no CDN allowed, no streaming media allowed) to keep the bursting to a minimum.
I do not recommend anyone starting a 100TB provider from scratch as the ROI is at best very minimal, even when done in large volumes. Only when a provider already has a large infrastructure with very large bandwidth commitments in place, then he could 'consider' the 100TB bandwagon and frankly: for most providers out there it is absolutely unattractive to provide 100TB under their actual costprice.
I am not specifically looking for full racks, but want to start out with collocating 1-2 machines and then eventually over the next few months collocate all my servers that i am renting at this moment. I would also not require all of the 100TB's but somewhere around 40-50TB/server.