Strictly from an economic standpoint: The $10T goes right back into the economy. That's $10T worth of STEM jobs and manufacturing and so on. Arguably, it should be spent more directly on schools and universal healthcare and so on, but $10T also creates a lot of jobs and healthcare benefits and funds public schools and so on so it's a tricky comparison to make.

From a non-economic standpoint: Aside from ensuring we don't destroy this planet, what is more important than finding out if we're alone in the universe? Not much, if you ask me.

(I realize finding algae on Saturn's moon doesn't definitively answer that question but it's certainly a uh... pretty big data point)

Look up the staggering amount of everyday conveniences invented by space exploration. Theoretically the private market would’ve filled this gap, but in practice we know the market will never be willing to spend the first few trillions on foundational research.

The $10 trillion will be spent regardless. Whether it's on luxury yachts, private islands, and political capital or health care, education, and exploring the solar system are choices.