There are many benefits that come with diversifying a retirement account with gold or Bitcoins (or other cryptocurrencies).
Gold is an extremely reliable and solid way to store money, since it's a way to safeguard possessions by protecting one's buying power/conditions (gold is not affected by devaluation the way regular currencies are).
Bitcoins and other cryptos may also seem as an alternative to regular retirement fund options or even gold, but it ain't (at least for now). Even though cryptocurrencies are still very unstable (monetarily speaking), they are (or were according to some experts) a way to store and easily transfer money anywhere. They are very promising in terms or transfers, safety measures (crypto-exchanges and users can get hacked, but the cryptos themselves operate in a relatively safe way), and even though it may be a way to earn some extra money (through trading/speculation), they are not comparable to gold when it comes to monetary safety (stability); that's why they might be a good investment option but the investor must be extra careful about putting a large portion of their retirement fund into them.
In other words, Gold is mainly reliable and stable (a way to protect you buying power and worry less about inflation/devaluation), and Bitcoins are an opportunity to make more money and a reliable and cheap way to transfer money anywhere
The answers would be "He sells some magazines" or "He decides he wants to be a writer.", since Gumption means to be resourceful or have spirited initiative.
Tom feels like he is of the "superior" race. He explains a book that he read that says that if they don't watch out, the white race will be "submerged" in just a matter of years. Clearly he believes that as a white man he is of the dominant race, and the fact that there is a book published about it and he can freely say these things shows that many people in society are of the same mind.
Some people today still think this way, although it is socially not acceptable to say it or act like it. Fitzgerald probably included this information to show how opinionated Tom is and set the tone of society at the time.
