A well-known mining machine project exposed issues during its operation in 2021 — not only profiting through reselling mining machines but also targeting Chinese users for fixed-point "harvesting" of profits, frequently adjusting hash rate allocations to suppress returns. From an initial promise of breaking even in 3 days, it was artificially extended to 30 days, then 300 days, and eventually became a joke claiming it would take 3000 days to break even. This process clearly illustrates some project teams' tactics: attracting early investors with enticing returns, then gradually eroding profits by changing the rules of the game. Looking back at the mining boom in the crypto space over the years, similar "harvesting" schemes are not isolated cases; they are the tuition fees paid by many investors. When choosing a mining machine project, it is especially important to scrutinize factors such as hash rate adjustment permissions, transparency of returns, and the credibility of the project team.