I played MTG for a number of years, has some mild success on the GP/PT/SCG circuit, worked for multiple of the big name singles sellers, wrote articles for money, collecting, and for a time made most of my money by 'day trading' cards at large events. I eventually sold out of both paper and digital and used the money to do things like pay off my car and support the downpayment of my house. Just a background for where I am coming from.
MTG seems to be the weird exception to the rule, and I think there are a number of reasons for that I am not really gong to dig into. Here's a quick example though:
For a quick real world data piece for individuals not as familiar, a Beta Edition Tropical Island sold for on average $662.40 in November 2010. In November 2020, it was up to $3395.90. That's a CARG of 18% over 10 years. Reference:
https://www.mtggoldfish.com/price/Limited+Edition+Beta/Tropical+Island#paperI don't have data to back it up, but I recall back in my day picking up Tropical Islands in the mid-late 90s for about $20-40 bucks each depending on the condition, so the true CARG could definitely be bananas.
In general, my experience and opinion is that MTG can function as an investment in 2 different ways:
1. you are effectively a day trader requiring lots of time and energy (keeping up with current format markets, travelling to events to buy/sell, looking out for banned/restricted announcements like a hawk, etc)
2. you are a long term holder of a somewhat illiquid long term play that is likely good provide returns, but carries some black swan risk greater than the stock market (WotC kills the reserve list, MTG paper dies and only digital is supported, you are identified as a high end collector and get robbed, etc).
Either way, I can see the potential, but I am no longer interested in the market.