Spot trading means you’re not technically “buying” the cryptocurrency, but instead trading your USD for it through either a market or a limit order. A market order means you agree to trade for the currency at the current market price. A limit order lets you put in a designated price at which you want the trade to occur, and when the currency reaches that price, the trade happens automatically. These orders then incur “maker” (for limit orders) or “taker” (for market orders) fees — though on Binance.US, there’s just a standard 0.1% fee.
Polkadot was designed to reward genuine investors and sorts out those that are only trading to make fast money from crypto. Investors that are well-engaged on this platform also help with decisions such as network fees, removing or establishing parachains, and network upgrades.

More rich young investors are opting to go without a traditional financial adviser. Instead, they are betting they can get good-enough investment options from do-it-yourself digital platforms that are cheap and easy to use. Many also want to invest in riskier assets, like cryptocurrencies and tech startups.
— “Those are among the more visible recent fruits of a well-funded campaign by Mr. Orban in the United States that stretches back a decade and now stands as a case study in how governments around the world seek to shape policies and debates in Washington, sometimes raising concerns about improper foreign influence in U.S. politics.”