Because contracts allow you to discover your trading problems more quickly.
Streamlined version: I advise you not to trade contracts, as I fear you won't be able to manage your positions well (or they themselves can't manage well).
If you have any of the following shortcomings in trading: making random judgments and frequently operating, holding onto positions, adding to positions against the trend, unable to calculate the liquidation price... then contracts will quickly inform you that you are wrong, rather than like spot trading: 'You just had bad luck in this cycle; in the next four-year bull market cycle, you will definitely achieve financial freedom!'.
If you trade ten times a year, then your sample size for that year will only be 10, making it difficult to summarize any patterns.
If you trade ten times a day, then in one month your sample size will be equivalent to that of the previous 30 years, providing too many opportunities for you to realize your trading problems. Moreover, for short-term trading, trading ten times a day is considered relatively low.
Those who believe that trading cryptocurrencies will ultimately lead to liquidation fundamentally misunderstand mathematics.
Someone who can't even calculate the liquidation price, when they say you will be liquidated, is akin to you dipping dumplings in soy sauce; it tells you that a person drinking a bottle of soy sauce will die from lack of oxygen—don't you think it's salty (idle)?