As far as I can tell, it is faster and easier to reload a lever action rifle than a bolt action, and they saw widespread use in the American frontier. Why is the rifle market dominated by bolt action rifles these days? Do they confer some advantage I don't see?
Action strength - most lever actions of the time didn't have very strong actions, which greatly limited the ammunition selection. The recent developments in smokeless powder also asked for a lot more from lever guns because of the different pressure curve, which a lot of lever actions couldn't handle. The only lever rifle I can think of that had an action strength comparable to bolt rifle is the Winchester M1895, which John Browning designed to handle modern smokeless powder and use spitzer bullets.
Tubular magazine - the tubular magazine prevented the use of new spitzer bullets since pointy things sitting on primers is a disaster waiting to happen. Again, the M1895 fixed this problem by using a box magazine.
Complexity and reliability - if you disassemble a bolt action and lever action, you'll see that a lever action has a lot more small moving parts compared to a bolt action. A bolt action is more or less a sear and a striker, so it's much much simpler. If you work a lever action, you'll also notice that when you eject a spent casing, the action is left wide open for dirt and debris to get in there and mess with all your little moving parts. The more complex design also means more expensive to produce.
Basically bolt actions are stronger, simpler, more reliable, and could fire much more powerful smokeless ammunition. The Winchester M1895 compensated for the vast majority of these weaknesses, but it was complex and expensive to produce compared to bolt actions.
I'm not sure why you think lever actions are faster and easier to reload than bolt actions. That's an erroneous assumption. Bolt actions are also much simpler to manufacture and maintain.
What advantage would a lever action confer?