the castle/manor is nice and has had some good events with bitcoiners, while illiquid it does provide some level of enjoyment from its utilization. unlike say owning some altcoin which is illiquid but also useless.
Altcoins illiquid
Last I checked I can liquidate altcoins with a click of a mouse, real estate however is either selling for heavy discount or waiting half a year and let's not speak of all the talking, travelling, meeting and administration.
The only useless altcoins are those that look most like bitcoin, many however innovate and some are already a lot more useful than bitcoin.
NXT for example allows you to not only save your money better thanks to no inflation, and save it with more certainty thanks to being 1000 times better secured against a 51% attack, but also pay people quicker thanks to 10 times faster secure validations, allows you to also message other accounts fully encrypted, launch or buy assets, sell or buy goods and services, and now even launch your own crypto.