Here we go again!
The Grand National is nothing like the race it use to be. The fences have been substantially moderated. Beechers has a far less deep drop and the ground is more or less flat on the landing whereas it was rising before.
Synchronised, one of the favourites ridden by champion jockey Tony McCoy, fell at a straight forward fence. He jumped it well and just seemed to buckle on landing. Obviously his leg had broken. No one's fault, it happens.
As for mending a horse's broken leg, it rarely ever works with a compound fracture. Their legs are inclined to shatter making repair difficult enough but, immobilising a horse is difficult. It has to go on a sling and accept that it cannot move. Few horses will accept this for more than a few days. It is not natural for them and they just give up the will to live then nothing can help them.
It is not a matter of owners being to mean to pay for treatment, horses like this are insured.
National Hunt racing owners are in it for the love of the sport, for every horse that pays its way by winning good races there are hundreds that do not yet owners keep trying because they love the horses and the sport.
As for the National being a bench mark for breeders, that is tosh. Although the National is a very prestigious race, it is not the most highly esteemed by trainers or breeders. Their ambition is to win the Cheltenham Gold Cup, a shorter but faster race. The National is one to win but if you asked most National Hunt trainers which they would rather win it would be the Gold Cup.
Horses die, I had to have a lovely three year old shot last year because he had severed through his deep flexor tendon. We could have tried to save him but, what would be the point? He would always have been crippled lame, and within a short time his good leg would give out from doing all the weight bearing. I have seen it happen more than once.
No one wants to see horses die, at least this year they cleared them from the course. It wasn't done last year because people like you who do not know the reasons for shooting a horse with severe injuries in a race, thought to drag them off course was 'wrong'. What matters to the horse, it has already been shot.