Speaking as someone under 40, I’m actually interested enough to know of many of those cues, especially Southwest, and plenty of other one-man-shop, handmade custom cues. That said, there’s no way I’m spending $5,000 - $8,000 on a custom cue, Southwest or not, hell not even $3,000.
Southwest was popular largely because a lot of pros used them back in the day, so fans saw them on TV and associated them with top-level play, they look nothing special. That exposure mattered. Today, most people simply don’t know these makers. Among my under-40 peers, there’s very little interest, no stories attached, no shared history, and nothing that really sparks conversation.
Ironically, I would absolutely buy a limited or special-edition Predator for $3,000

. At least I know the brand, the tech, and that it’ll likely hold value. Also, half of the pool room are under 40 so I'm holding a head turning cue then
However, there is an exception: Asian market (China and Southeast Asian) - they would spend $10,000+ and wait 2+ years for a high-end custom cues. The re-sell market is huge other there too.