I think you nailed it. TS is great but is in a middle ground niche with more targeted alternatives squeezing it from both sides:
1. If you actually need strong security, you are likely to go with open source zero trust or their commercial versions.
2. If you don't need strong security, you will often view VPN an insurance policy (TS simplifies but is still more difficult than 'do nothing').
So you end up with a relatively narrow band of 'use cases' like NAT traversal; semi-privacy; access to private IP hosted services. Enough to sustain a venture funded company?
1. If you actually need strong security, you are likely to go with open source zero trust or their commercial versions.
2. If you don't need strong security, you will often view VPN an insurance policy (TS simplifies but is still more difficult than 'do nothing').
So you end up with a relatively narrow band of 'use cases' like NAT traversal; semi-privacy; access to private IP hosted services. Enough to sustain a venture funded company?