Because:
1st: What they think of when they hear aliens is of course the reality, it's not like we're most likely to discover microbes on other bodies (not planets because, well, Titan, Europa, Enceladus...). And yes, microbes on other bodies is worth the money, actually it's quite awesome.
2nd: Only living species are worth noting, just like on Earth where no one cares about iron ore or oil. Our economy is built on these? Oh...
1st: What they think of when they hear aliens is of course the reality, it's not like we're most likely to discover microbes on other bodies (not planets because, well, Titan, Europa, Enceladus...). And yes, microbes on other bodies is worth the money, actually it's quite awesome.
2nd: Only living species are worth noting, just like on Earth where no one cares about iron ore or oil. Our economy is built on these? Oh...