Because you have to? Your other options are to be born wealthy, start an independent business (which also usually requires up front capital), or live out in the wilderness.
As the alternative, you try to find positions that don't look like they have a pile of spin buried in them that seem to be hiding something. You look for red flags and then interview the set of employers that is also interested in interviewing you.
You can reduce the filter and wait for the interview processes to reduce false positives but from my experience, being cynical is a good filter to save me time from working in toxic positions at toxic companies. After interviewing and working in business environments, you learn more and more of the spin techniques everyone seems to use.
It's interesring how being critical of business ads is viewed negatively, yet it's perfectly fine for businesses to have full day interview processes, background checks, resume filters, skill tests, etc. Hiring businesses obviously don't trust you and your advertising, why is it assumed you should trust them? Trust is a two way street and has to be built and business relationships are growing increasing transactional and shorter term which doesn't exactly instill a sense of trust between people.
