Can I double my money through the upcoming Segwit2x fork? Today, I have received an e-mail from GDAX that says:


  We wanted to remind you that the upcoming Bitcoin Segwit2x hard fork is projected to take place on November 16 and will result in two bitcoin blockchains.


And especially interesting:


  Any customer storing Bitcoin (BTC) on GDAX at the time of the fork will be credited with an equal amount of the Bitcoin2x (B2X) asset on the Bitcoin2x blockchain. GDAX will continue referring to the current bitcoin blockchain as Bitcoin with ticker BTC and the forked blockchain as Bitcoin2x with ticker B2X


Does this mean that I have the double amount of money after this fork? If yes, why should I not buy a lot of bitcoins before the fork and sell all Bitcoin/Bitcoin2x immediately after the fork?
The "Segwit2x" fork is scheduled to activate at block height 494,784. After this block, there will possibly be 2 independent blockchains that grow independently of each other. If that happens, then any BTC you held before block 494,784, would also be available on the B2X fork. 

This doesn't necessarily mean you would double your money. It's possible, but it depends on how the market prices both BTC and B2X. For example, if you held 10 BTC @ $5000 before the fork, and then the fork happens and exchanges come back online and the market prices BTC at $2000 and B2X at $2000, your 10 BTC + 10 B2X would be worth less than before the fork. It's impossible to know how the markets are going to react to the fork and how messy it's going to get.