..why spend money for only a few percents of possible customers...
Because customers are optimists overestimating their abilities 
- you should see how many idiots are navigating big sea-going boats around here, without a clue as to what they are doing. Even if it is pretty obvious they will (and should) never take their overpriced vessels beyond sheltered waters. Your logic is good, but it is easy to underestimate the vanity of new boatowners... ok