You mean you quit before having your dream job/career lined up? Just judging that by the "if you can't find work in a few months" Seems a bit......dumb to me.
As to the giving you your job back, its not that other bosses are just jerks and hes a great guy. Most bosses when they have somebody quit/fired/promotion/whatever, there is now a vacancy that needs to be filled. They can't just leave it vacant for a few months on the off chance that person might be back. So it gets filled, and now if you come back, they can't just up and fire the new guy, even if they'd really like to. And trust me, most of the time they would love to get back that guy thats already experienced and doesnt need to learn everything. And unless the business is expanding or they have a ton of turnover, they usually can't afford to just tack on another employee that they don't particularly need.
Can even be much more detrimental than beneficial. Higher costs (employee labor is usually one of the biggest costs in most businesses) mean they have to increase their prices on things. Higher prices means they can't be as competitive with other companies and they lose business. This makes their costs per unit even higher (ex: building rent is $5000/month whether they sell 10 units or 1000. split among them all its a cost of $500 or only $5 per unit) which in turn makes it even harder for them to compete. Now the business is going under and ALL the employees are out a job. All because an incompetent manager. Worst case scenario, but I've seen it happen several times before and the root cause of it was things like this
As to the giving you your job back, its not that other bosses are just jerks and hes a great guy. Most bosses when they have somebody quit/fired/promotion/whatever, there is now a vacancy that needs to be filled. They can't just leave it vacant for a few months on the off chance that person might be back. So it gets filled, and now if you come back, they can't just up and fire the new guy, even if they'd really like to. And trust me, most of the time they would love to get back that guy thats already experienced and doesnt need to learn everything. And unless the business is expanding or they have a ton of turnover, they usually can't afford to just tack on another employee that they don't particularly need.