The premise of your question is that you can buy physical safety like you can buy a t-shirt at the store.

This was not what I was trying to put across. What I was thinking about was perhaps the exact opposite.

Many people train MA for the primary reason of self defence, many with the belief that they will then be 'competent' to defend themselves.

To become competent in any style (agreed competent not being a defined standard) will take years and will be a significant investment.

So I realise self defence training is far more of a...gamble than a purchase.

My thought was are we putting our money on the wrong horse in MA? And also self defence products.

I agreed with pretty much all your post but then you made the following statement which I think is a commonly held view (of flawed logic IMO).

Actually, my post premise was intended to raise debate against this statement.

Since physical self defense is probably the last line of defense you have, any advantage you can get with it is valuable. This is why I think that training MA is value for money.

I think this is the human nature response to focus on the worst case, low probability outcome.

It is the like driving to the beach after a couple of drinks without your seat-belt on, then not going for a swim in case you get attacked by a shark.

Also consider:
-For many people the advantage they get from MA may make very little difference anyway e.g. 5'2 woman vs. 6'2 bloke
-There is debate on what is effective MA
-May some MA hinder Self defence?

Prizewriter says:
Another factor to consider in physical "self defence" training is flight training. Sprint training, running endurance, climbing, parkour etc.... All skills that can be trained.

Ronin says:
Avoiding the avoidables.

and Leo Again
...you can get a lot of information relatively cheaply about the stages of criminal behaviour and principles of self defense (particularly awareness and avoidance).....

All this can be done for practically no investment.

So is martial arts training really value for money?
Or is someone whose priority is only self defence backing the wrong horse?