We have almost exclusively TBs, which generally lead very regimented, consistent schedules during their racing years. Every single one has acclimated and they all love being outside 24/7… I almost never see them in the run-in unless it is miserably cold & rainy. Snow, sleet, sunshine, they’re all outside eating/grazing.
Couple of things: people reinforce the gate-standing/walking by bringing the horse in any time it acts up. You mentioned he runs until someone brings him - sounds like he has learned if he runs around, someone will come and get him and bring him in… This is a common mistake made by people, and they don’t realize how it just reinforces and encourages the behavior of running.
Most horses who have not had 24/7 turnout are anxious to get back to the barn because that’s their schedule, not because it’s good for them – and it’s also where the grain is. Make sure to feed away from the gate, and don’t bring him in ever and then grain him.
Secondly, he would do much better with a friend. Most of the time that there is paddock misbehavior, from pacing, fence walking, calling, etc, is because they’re acting out because they’re unhappy with their lack of social support - horses are social creatures, and need other horses to feel secure.
I have not had a horse “not tolerate” 24/7 turnout. It does take time, and you have to go the route of “benign neglect” and not reward their misbehaviors by bringing them in. It usually takes about 2-3 days for a horse with a friend, and 2 weeks of consistent turnout with no being brought in over misbehaviors for a horse with no friend.
Does he have a shed to hang out in?