We already use GitLab for all our source repos, CI/CD pipelines, and had been using it for issue management as well — all fully self-hosted. The hope was to drop Jira, which was also being used for project planning, and fully adopt GitLab, but the costs were simply unjustifiable.
Basically GitLab ended up being a full order of magnitude more expensive. Even with discounts, which got things closer (but not all the way there), the fear was after a period of time, the discounts would be ended/phased out and we'd be stuck.
I'd love to see those features that compete directly with Jira (like roadmaps and multi-level epics) come down to the Premium level, which is more price/feature competitive.
We love GitLab, but find ourselves stuck using the free tier and paying for services we don't love, rather than supporting GitLab. I'd suspect we're not alone there, either.