Beats Las Vegas in 2/3 aspects. Pooled mining would also return more than 100% right now, but with zero fun and much time wasted for a wimpy return (or considerable risk if you scale).
You fail to take in account that every day you don't find a block, you
lose 0,55 BTC that would otherwise be in your bitcoin wallet. Those "wimpy" losses add up very fast.
So for every 100 days you find nothing, you are losing over 50BTC or a whole block because you're not in a pool.
Variance only evens out in the long term so it could be another 100 days or even 3 years before you find your next block.
Just because you win the lottery once doesn't mean it's going to happen again anytime soon. Just because you found a single block with a 5870 doesn't mean it's going to be a regular event.
However, a pool with 3000 ghash/s finds blocks in about 20 minutes average.
Your share of the current block doesn't necessarily even have a fee for variance reduction if you mine in a 0% pool like BTCguild.
It seems some people get overly enthusiastic about solo mining just because they got lucky once