Great post. 
I think these asset classes are actionable if you have deep knowledge in the given niche. E.g. if you are into retro consoles, likely you can tell what ‘things’ (games, hardware?) are good investments in that space. Otherwise, it’s an uphill battle to learn about something you haven’t spent years delving into.
I heard on the InvestED podcast about a lady who’d buy fur coats at yard sales. She’d know exactly which one was worth how much, and she’d push for a discount on that price.
In an Invest Like the Best episode, Patrick interviewed a guy who was in the business of exploring new asset classes, and he invested into a range of things from watermelons to Instagram profiles to well-reviewed Airbnb accounts.
In the art niche, I read in a Cody Shirk newsletter (this one) about the process he used to buy paintings. I don’t know if his approach would work in the UK, although replacing ‘Craigslist’ with ‘Gumtree’ makes it sound actionable. I’m curious if anyone did anything like this though.
I think the takeaway is, investing is way bigger and more interesting than most people expect.
As always, none of this is advice of any kind (financial, life, etc), and I hope no one kicks in the door tomorrow morning at the office with a resignation letter in hand, ready to trade retro game consoles! But I do hope to hear of alternative investments I’ve never thought of. Love learning.