Most people are terrible at salary negotiation. Based on various studies with some degree of variance, overall they suggest about 55% of men do not negotiate their wages, and about 70% of women do not negotiate their wages. That is NO NEGOTIATION AT ALL.
Bear in mind that a lot of people are pretty desperate to get a paycheck. You can pretty easily take yourself out of the running for a lot of jobs by trying to negotiate salary (or by doing so clumsily) particularly when there are multiple qualified candidates for the job. Not saying that more folks shouldn't negotiate their salary but many times they are not negotiating from a position of strength. It's one thing if you have a nice pad of savings and can afford to say no to an offer. Not everyone is so lucky. I've been in both circumstances myself at different times so I understand how hard it can be to negotiate when not getting the job at all is a worse outcome than getting paid a sub-optimal amount.
That said I agree completely with what you said. Negotiation is a very valuable life skill. The sooner you get good at it the better.
This is the wrong way to approach the problem of being (reasonably) desperate to get a paycheck. You are either worth the higher salary or you are not. Being worth the higher salary means (by definition) that given time you *will* be able to find a job that pays that much. This is a negotiation position you can take up. If you don't feel too aggressive, agree to an "evaluation period" (say 6 months) for the lowball offer after which they will either bump you to a decent salary or you will find another job that will pay better. You will have been looking for 6 months by that point. If you are feeling aggressive just say up-front that they either offer you a decent salary or they'll end up with someone who's not very good ando/or not very confident, and they'll have missed out on a great new person in their team. You might find them suddenly very interested in you, because now you've expressed openness and confidence.
If *you* don't believe in yourself, why would you expect them to?
Now, if you're actually desperate for a paycheck, to the point of not having a roof over your head, then you just don't have negotiation room. Just negotiate for the actual job, and use the job as a springboard for your future. You still don't accept a job that doesn't actually pay enough to get you out of the danger zone though, because that just ties you down without providing a solution. As the saying goes, if you find yourself in a hole, stop digging.