The main reason HT are so expensive is that they can name their price as the leader in their field.
Also aspects like licensing and other legal type costs are contributing more and more and covid has inflated production costs, resources, transportation across most industries.
They are generally focusing on licenses while they are hot and new.
SST has come out multiple times and said they started out with figures that had either less popular licensing demand and/or were old enough IPs where they knew the licenses wouldn't be cost prohibitive to acquire.
Someone who wants to make Hunger Games figures 15 years from now is not facing the same situation as HT trying to get all the Marvel licenses today.
HT started out with retro licenses. Rambo, Robocop, Terminator, Aliens, Predator, etc, etc. But that well ran dry.
Over time, my guess is we'll all see more movement towards the 1/12th scale. Maybe a little bigger. I think 8 inch figures is about right for getting more cloth/detail oriented stuff in play.
The other factor is how predictable is reusing existing R&D and molds going to be? With the MCU, after the first Captain America dropped and you could see the groundswell, you could project probably 3 full Thor movies and see the pattern for four future Avengers movies. That's giving you a lot of mileage out of that Thor Hammer accessory.
But sort of one offs? Like I doubt HT would have done Avatar Jake Sully without understanding there would be future sequels. Albeit a long time apart. But I doubt you'll see stuff like Appleseed Briareros ever again.
Part of the game is being patient. To help fund the new prequel Star Wars movies, Lucas allowed the Power Of The Force 4 inch line to return to stores. People went nuts over it. Then there a mass dumping when Phantom Menace came out. You could get a POTF AT AT for 9.99 at some ToysRUs locations in the old days. Yes, the big one.
At some point, the market will likely collapse. It happens to all lines and brands eventually. HT has had a long life cycle that's a little unusual. Like 80s GI Joe RAH, they had good timing on their side. They keyed in during the massive uptick from modern military 1/6th during the early 2000s. Lots of conditions made that possible but were unique. Widespread internet access and home PCs weren't really a thing until the late 90s. Larger shifts to ECommerce and online retailing didn't take hold until half a decade later. Formalized online payment systems changed the game and web development to support that changed the game quite a bit. There were some overall price controls coming from the 2008-2010 era of the economy just being tanked.
When HT collapses, hope you are in the right place/right time to buy in when someone is dumping their collection. If you are still in the game that long.
Part of the equation is a lot of potential collectors are opting out because of the FI/RE movement ( Financial Independence/Retire Early) and the minimalism movement. You need space and time and money to collect and there is a clear generational demarcation point at work here. Are you really going to see so many 20 year olds collecting HT stuff now? At price points at 300 a figure in some cases?
HT is expensive in part because it has survived. It's survival was dependent on a host of many other complex issues that range outside of the hobby and 1/6th in general.