If you buy obscure name extensions it's likely there is no market for them yet, so no market, no value, supply and demand etc.
Have a look at peoples portfolios, most are full of names registered 10 to 15 years ago, so if you are going to gamble on the future you have to be prepared to hold the names for the long term and if like the .biz and .info it doesn't work out, well, you just have to bite the bullet.
Some access methods into the domain industry may look easy but the cost is normally a loss of investment, that's the reality.