Red deer have no natural predators just now and plenty of food - they will continue to increase in number.
You will also find that a lot of those that stalk deer are not "the gentry".
It does make sense to manage the Scottish red deer population through limited hunting of both stags and hinds in the relevant seasons. Red deer are a valuable source of revenue for the highlands, both in direct fees associated with stalking, but also from tourist Pounds invested in local communities and employment.[1]
I can appreciate why there is some concern regarding the potential introduction of wolves and their effect on the deer population. However, I think that also needs to be considered in light of the economic benefits of such a re-wilding. How much revenue would wolf hunting and tourism bring to the highlands?
[1] http://www.scottish.parliament.uk/ResearchBriefingsAndFactsh...
It's also worth pointing out that deer hunting in Scotland is a very, very different experience to deer hunting in America.
What happens in Scotland is that you get taken up into the hills by the gamekeeper, a specific animal is pointed out to you, and you shoot it with a high-powered telescopic rifle from a large distance. You pay very handsomely for this, and you don't even get to keep the animal. You're certainly not allowed to wander around on your own with a gun!
I agree this is unlikely to happen on many of the larger estates, but there are still opportunities, including joining an existing syndicate or leasing land yourself.
I'd also point out that generally you have the right to decline a specific animal pointed out to you by the gillie, but need to keep in mind it may be the only stag you're onto all day!
Also define "large distance." I'd contend there's not many deer highland stalking shots taken at distances greater than 200 meters and most more likely between 100-150 meters.
If you do go out on your own, what do you do with the carcass? Phone in and get the keepers to come and pick it up? I assume it still belongs to them, and they've adequately briefed you on where you're supposed to go and what they want you to shoot.
If you're unaccompanied on someone else's estate, then it's your responsibility to bring the carcass down off the hill. That usually involves tying yourself to the carcass and dragging it (or if the hill is steep enough, it will drag you) down the hill. At the bottom of the hill, or along the way a little, you are likely to have parked a quad or utility vehicle. The carcass remains property of the estate.
If you've leased land, or as part of a syndicate, then you still need to remove the carcass from the hill and transport it to a cool room, where you butcher it yourself and a game dealer will collect it the next day.
Carcasses are always gralloched immediately on the hill, and the entrails left behind.
Part of the training in DSC 1 and then much more thoroughly in DSC 2 is how to properly butcher a carcass.
http://basc.org.uk/sporting-services/basc-training-courses/d...
http://basc.org.uk/sporting-services/basc-training-courses/d...
There are also specific basic carcass and butchery courses:
http://basc.org.uk/sporting-services/basc-training-courses/c...
In the Scottish Highlands a red deer stag isn't really prohibitively expensive, usually around the £450 mark. Hinds, later in the season, are much cheaper.
The real expense is everything that goes with it - the travel to the highlands, accommodation, appropriate clothing and equipment. I think you could probably cull one stag for £1,000 all included.