> If self-hosting Sentry is a problem I would start doubting the skills of your 
  > tech team.

I can't think of any team I've worked at in the past year for whom reading the self-hosted Sentry docs and standing up an instance would be impossible.

However, my experience is by and large at early-stage startups, and so I also can't think of any instance where I'd want to have my team working on that when they could be working on adding value to our product. If I can pay Sentry to handle setup, scaling, maintenance, etc (and I do!), then that's worth it when weighed against the dollar and opportunity cost of having my team handle it.

That's not to mention maintenance or other issues.