A platform advertises a fixed, guaranteed return — for example "2% daily" — that sounds modest day to day but is mathematically impossible to sustain through genuine investment returns over any meaningful period.
Early investors really do get paid, which is the entire mechanism that keeps the scheme alive: those payouts are funded directly by money coming in from newer investors, not by any underlying trading or business activity.
The scheme continues only as long as new money keeps flowing in faster than it's paid out. Once recruitment slows, or the organisers simply decide to stop, payouts stop and the platform disappears, often overnight.