Explain Like I'm 5 (ELI5)

It's because of competition. Someone else will find a way to produce your product faster, better or more of it at the same costs, with less people, using new technology which requires a higher turnover but has fewer costs, and you will lack capital to invest in that machine to make your business competitive again. Even if you do have it, there are now two companies with that machine who invested capital and require a higher turnover, but the market is limited and one of you, if not both, will fail to bring in the return on the investment, let alone make enough money to invest in the next machine. That effect can be seen all the time, the current best example in Europe is the automotive industry, the next one will be giga factories, AI data centers.