Whilst people may get attached to their wines or can't motivate themselves to sell, the fact is, for every bottle you have you can drink it or sell it at somewhere near market value. From an economic/rational point of view drinking a bottle from the cellar that is worth, say, £1000 is no different from paying the same price retail (assuming provenance is equal.)
It puzzles me as to why people who refuse to consider selling wine, especially at a profit, like to support their local merchant as if this were an act of charity. A retailer is just doing the same dastardly deed (buying and reselling at a profit.)
I must add, I'm not a 'flipper' myself (can't be bothered), but I don't get angry if others do this any more than when I see wines being sold in a shop at (what I consider) is an 'over-ambitious price.' The latter affects me more that the former in any case.