I'm not pro-bitcoin or proof-of-work, and it does seem like a poor trade-off, but there is _some_ foundation for it's value.
In the end, it is kind of similar to gold. Gold has a limited supply and nobody can fake it. It's worth a lot because it takes a lot of energy and resources to mine the gold, and it's been around long enough that there is a certain respect for it and the fact that you can't just "make' it out of thin air.
Bitcoin is pretty similar in those ways.