In a worst case scenario, this means I practice for 2000 hours in 10 years to ensure that I am ready for those 5 minutes.
Is it just me or does that make no sense whatsoever?
Hell, not even I am that paranoid.
(It would make more sense to embrace religion and spend 60 years preparing my soul for being eternally dead: the investment-return ratio is considerably better)
You and me see eye to eye. Go back and look at many of my post...only you said it much better.
I think aikido or any martial art as a means of self defense or fighting is a waste of time for the reasons you state! There are many more effective ways.
To add, you have a higher chance of dying from high cholesterol and diet induced diseases, so you are better off practicing good nutrition and exercise as a form of self defense.