If you are talking about a motorcycle, then YES! absolutely wear a helmet! Better yet, sell the damn thing and buy something ( read: virtually any other motor vehicle) that has a lower death rate.
But, if you are talking about a regular bicycle, than I would say it depends on where you ride, and if you lack skill or balance.
If you are a complete klutz, then you should probably be wearing a helmet while you walk, let alone riding a bicycle.
If you plan on doing stunts, tricks, riding on heavy-traffic roads, or plan on mountain biking, then a helmet is advisable.
But, if you plan on doing small neighborhood riding, and bike paths, then no, you probably don't need a helmet.
You can liken the bike paths and small neighborhoods to wearing a fireman's suit while lighting a cigarette. Is there a chance of danger? Theoretically, yes, but it's overkill in the real world.