How do startup investors actually get their money back, and how long does it take?

A startup investment is a share of the company's future: there is no fixed repayment. Returns usually come from an exit, when the company is acquired, lists on a stock exchange (IPO), or your shares are sold in a secondary sale. Some companies pay dividends, but early-stage startups rarely do.
Exits take time: most take five to ten years, and some longer. Until then your money is locked in and usually hard to sell.
Many startups fail even with careful selection, and a failure can mean losing the whole amount invested. Investors therefore expect a few successes to make up for many losses, which is why spreading money across several companies matters. Capital is at risk: crowdfunding investments are not covered by deposit guarantee schemes, can lose part or all of their value, and may be hard to sell before the end of their term.