It's one of those personal things. Today I spent a few grand on a numberplate that is personal to me (no it wasn't 1 D which went for £285k + fees and VAT!). It'll remain on a retention certificate until one day I decide to stick it on a car. It won't make me any money between now and that day, unless someone bites my arm off for it and I sell it, and it probably won't make me any money when I do stick it on a car unless it becomes a topic of conversation somehow and someone decides to do business with me because they remember me because of it. However it was worth the amount I spent for me to take control of it.
Domain names have more of a use but a first name, if you aren't somehow known in business by that, is a lot like my numberplate; not much value but one still likes owning it perhaps for vanity. I've never been an enthusiast of
[email protected] (or similar) email addresses. I'm lucky enough to own my surname in .com and .co.uk which not a lot of people on the planet can claim. I regularly turn down offers for it. Do you turn down many offers for dean.co.uk? If not, then keep it. If so, decide how much you want for it and then deduce whether someone else, probably called Dean (or with a newly born son called Dean) is prepared to pay that amount to compensate you for losing it. Otherwise stick it on the shelf and it may come in useful one day if, somehow, your persona becomes ubiquitous when most people and media establishments utter the word "Dean".