I expect that the major positive impact of tourism was providing motivation for local governments and local citizens to crack down on poaching. I am skeptical that you can convince every single poacher to stop poaching and become tour guides. I am also skeptical that the person paying money for ground elephant tusk elixirs is going to view a vacation as a suitable substitute.

Reducing demand certainly helps, but tourism and poaching are not exclusive markets, you can have tourism and poaching happening at the same time -- and demand for one isn't necessarily going to reduce demand for the other. If 100 people are giving tours, and 20 people are deciding that they'd still rather just shoot elephants because they don't like dealing with tourists, then you still end up with zero elephants. Reducing demand is only going to be one part of the puzzle, a slight reduction isn't enough on its own to solve the problem.

And regardless, looking at market demand as a part of the solution is still kind of missing the point. Sure, we might be able to leverage some market forces to help with the overall problem, but it's still a problem regardless of what the market says about it. The market in this case is at best a tool, it doesn't define what the right outcome should be.

It doesn't matter if the vast minority of people rich enough to spend money on this prefer elephant tusks or tours. It should not be their choice to make. We don't want the market to decide whether or not we have mass extinctions. If we end up with zero elephants, saying, "well, the market just didn't create enticing tours, so we'll never have elephants again" is not a valid response.

What percentage of the population is rich enough to go on wildlife tours to another country? They don't have the right to choose for everyone else whether or not elephants go extinct.