Four Questions (I'm better at questions than answers and sometimes questions are better answers than declarative statements in any case.)
1st Question: how could it be worth more to someone else than it is to you?
2nd Question: if you have the money to spare, and knowing it is OK to use it to expand if you choose, what expansion costs are there that would require the expense up front in money rather than in work and time? (Of course this comes from my perspective as a control freak. Personally I would invest a certain percent of profits into expansion as the money is needed in any case. Unless you are purchasing a lot of specialized programming and the like, I usually find that I can't learn how to use my tools faster than I can afford to buy them and it doesn't pay to have a fancy camera or whatever sitting in the closet or a program on my computer that I do not know how to use.)
3rd Question: what makes anyone think that or any domain name is worth that kind of money? I guess people do pay for unused names just because they are reserved, but the big money people pay for domains is rightly based on the reputation they have, proven income, established link source etc. If you are talking about an unproven name what gives it any real worth to anyone but an uninformed newbie?
4th Question: do you have an alternative name that you think would work just as well and will you be happy with it five years now if you see someone else thriving with the "treasured name" you sold off even if you got a good price?