Yes, and they come with different architectures, SLAs,... not so easy to pick one. Their features may not map 1:1, not so easy to implement a multi-edge solution.

Certainly. But I think that comes with the responsibilities, to be ready to switch a third party provider if necessary. Nothing is ever certain.

People are ready to switch to third party but such plan comes at cost.

Instant switch means really high cost (two contracts) and also maintaining and testing it regularly. Also means you are limited on advanced features and most likely stick to basic features, reducing your ROI.

Most people are ok with a switch that would take days to weeks, reimplementing basic stuff during initial migration, then iterating on more advanced features. You run at risk to be down for hours to days. The cost of 2N or 2N+1 vendors is just too high to justify it.