Construction tools.

It is becoming big business. But big business doesn't mean high margins, large corporations that work in high competition field don't have high margins.

The reason is someone is dumping their bitcoins. Some got in earlier, maybe at 30 or even 5. And also companies that mine (AsicMiner, Avalon) might be selling their bitcoins.

Yes, it's possible, maybe in 10 years.

Invest in bitcoin only if you can afford to lose it. There are many ways to invest that are not tied to fiat currencies, such is real estate and stocks. Precious metals too, but it might be too late to buy gold.

Diversify it with bitcoin, but only a small part, and long term.

I looked at seals with club and I think there were more players before. Not playing any more, but maybe I will if there is a btc site with enough players.

Too late for GPU, maybe if you have very cheap electricity it's worth it. But return isn't much. I wouldn't bother building a GPU mining machine even with very cheap electricity. Asics are hard to get, maybe order KNC miner or invest bitcoins into securities.

Post and maybe buy some at auctions.