This was said a lot to us during COVID. However, my coworker, who was laid off in March 2020, well her unemployment was more than what we made, then she got a job making more than what she made previously.
My other coworker, who did not get laid off, would regularly repeat “we're so lucky to have a job.” She has a PhD from Yale!
However, I read somewhere that if you think about it, your company should also feel lucky to have YOU (provided you are a decent worker and good at your job). When interviewing, it shouldn't be solely prove you want to work for us, but also prove why I should want to work for you.
While yes, you should be grateful to be able to support yourself, in the sense you're also grateful not have serious health concerns, this doesn't mean your job can just abuse you because “YoU sHoUld Be GrAtefuL.” For example, if you're in a relationship, you should be appreciative of a positive relationship, but if your relationship is abusive, you shouldn't just keep taking it because you feel you should feel grateful to be in ANY relationship and someone is doing you a huge favor by “putting up” with you. It should be mutual, where you're both happy with the situation and both feel appreciative of what the other brings.