Novena's a pretty amazing project, but it's not nearly as polished as this purism laptop appears to be. It's (intentionally) a hacker friendly box with lots of space and less integration than a normal laptop. It even uses a RC hobbyist style battery. Novena is a labour of love driven by a particularly skilled person.

To design and mass produce a laptop as slim and well integrated as the Purism laptop is significantly more work. To do so having never produced a laptop before would cost even more so. $250,000 really is a small amount of money when you're trying to mass produce cutting edge consumer electronics.

Of course they may (almost certainly do) have other sources of investment.