How can there still be people who don't know what left side and right side mean?

In simple terms,

Left side means entering the market when prices are falling, buying more as prices drop.

Right side means entering the market when there are signals of a bottom, buying when the rebound starts.

Left side is suitable for large funds + aggressive strategies; if the price drops, you can add more positions. If small funds get stuck and can't add more when the price drops, when it goes up again, others are making profits while you're just breaking even.

Right side is suitable for small funds + stable strategies; confirm the bottom, enter the market after a reversal. Although you might miss some profits, it’s safer.