Why clients don't hire even though proposals are 50+

[isildurikc]

I am a beginner at Upwork and have applied for 10-12 jobs. I got one already. But I noticed that in most of the posted jobs, the clients don't hire anyone, let alone take an interview. The number of the proposals is 50+. I see that "Last viewed by client" a few minutes ago, hire rate is more than 50% and the jobs had been posted for more than 1 or 2 days. What's the catch here?

[feed_my_eyes]

The client may have found a freelancer elsewhere, or their project was cancelled, or they were hit by a bus, or they got tired of reading through dozens of useless proposals from unqualified candidates, and gave up. 

A hire rate of 50 percent is obviously not great, either. I wouldn't bother with clients like that in the first place.