I wouldn't bother with biking if I didn't enjoy it. It's not just the higher milage or the sense of only transporting myself without four additional empty seats, or the increased acceleration or the sheer ease of jumping onto the saddle and revving the engine. It's like Luis' convertable... only I don't get the wind flowing through my hair since it's locked in a full face masked helmet. I look like the old Stig with all my gear on.
Biking is fun. Biking is unfortunately all about knowing you have a bizarrely high fatality chance since morons driving coffins don't notice something a third of thier size, and having to adjust and take into account driver's moronic tendancies. Today alone I had four white vans pull out from junctions cutting across me. Oh and a bus tried to pull out while I was half way through overtaking it.
My main problems are my last second checks into turns (named 'lifesavers' for a reason) and my lane discipline at roundabouts. Fortunately, I don't need help stopping safely for morons and restraining myself from flipping them off.
Biking's also cheap, but all the money I get from the savings (£700 second hand bike? 100mpg? <£100 road tax? 70mph and looks like a Bat Out of Hell? As old as me but will run until the end of time? Sorted!) will be thrown into my insurance and possibly on private medical insurance...