That's the whole process if you get hired. In the hiring process at my company we'll maybe give take-home assignments to three candidates for one role. So by the time you're doing our 4-hour assignment, you have about a 1/3 chance of getting the job. Not a bad deal in my opinion.
If, given you are at the beginning of the "do onsite interview loop" stage, you have a 30% chance of getting an offer, you will need to do NINE of those to have a 95% chance of having gotten >= 1 offer.
So yeah that is kind of a bad deal assuming you already have a full-time job and/or family/kids. I guess if you're single and unemployed then it's not so bad, aside from the fact that being unemployed greatly cuts your bargaining power?
As a whole unemployed cuts your bargaining power, it's natural to say "why should I leave my job" as a counterpoint. The flipside game is if you can arrange multiple offers at once (i.e. a high value candidate) while unemployed, it's a fantastic feeling. Then it's more like an auction, and auctions can get irrational. Turnabout is fair play and all that
