Not in the sense of starting down the path to a long term future. Much of your doubts can be mitigated simply by expanding beyond one planet. I believe resource limits and technological disaster of an intentional (bioweapons, nuclear war) or unintentional (GW, ozone layer, water/air pollution) nature are far more likely to end our civilization than cosmic events (even the near term potential for an asteroid impact). With two or more planetary civilizations we should be able to recover from any of those. I'm also concerned we have a limited time window due to resource limits to make the leap to space,

I also think the best way to expand our technology to deal with most civilization ending and extinction type scenarios is to expand into space.

Regards,
Mark