Don’t make the mistake of humanizing a company. A company is not a person: it has no loyalty or sense of decency, and no moral obligation towards your wellbeing. You are a worker: you provide work for money. If you were a farmer selling lettuce to a supermarket and a new supermarket came along offering more, would you sell your lettuce to the old or the new customer? The new one, of course. Same here. Because the supermarket won’t think twice about ditching you when it finds cheaper lettuce elsewhere.

This said, your manager will have feelings about it, so you want to deal with that. Just be frank with him and manage his expectations: “Obviously I’ll help the transition as much as I can and I’ll always be grateful for the chance, and let’s stay in touch in case you need anything when I’m not here anymore.” Talk to the man, not the company. The company doesn’t care.

Take the chance dude, some boats only pass once. After you have “those” names on a CV, more doors will open.