Thank you for detailed answer, RJ.They are cheap because there are 456,976 of them and not enough demand to raise the current price.
I'm glad you called them cheap, because I also think 4-letter .coms (4LC) are undervalued. They are liquid assets, which is pretty much the holy grail achievement of dominating. Even a $100 liquidation value for non-premium four-letter combinations is not insignificant, because having a reliable liquidation value means the assets can be used as store-of-value, a currency, collateral, or type of security. If a big investor enters the market, the wholesale liquidation value will assuredly go up.
456k might sound like a lot, but it really isn't. Consider the similarity to Bitcoin that also has a limited supply of 20 million BTC. There will never be more than that. At a $150 valuation for any combination, that is only a theoretical $69 million dollar market cap (1/4 of Dogecoin's) A wealthy investment group could easily swallow the entire aftermarket of 4LCs at this point and the prices would rise accordingly.
Chinese domain investors poured a lot of money into buying 4LC a few years ago and achieved a $1000 liquid value for domains that met their criteria. Any domain that didn't contain a vowel or the letter V was valued at minimum $1000, and were called "CHiPs" (Chinese premium domains.) This type of $1000 valuation could happen again for all 4LC if investors around the world caught onto the concept of buying these domains as assets.
This is not investment advice of any kind, just my own personal opinion of the market.