Actually they kept a lot of benefits given during the Revolution, even during Napoleon. Nobles become taxable, the third estate (the common people) got a political voice, clergy lost a lot of power, military positions became more awarded by merit than nepotism, wealth, or nobility, laws were equalized and started applying more to everyone, the press became more free, spending became focused on the public, and more. There was a reason Beethoven was writing a song for him, up until he crowned himself Emperor. Until then, he was a representative of a mostly beneficial revolution. And yes, that crowning and obsession with war was an unfortunate move, but a lot of the changes stuck for awhile even after those bag parts lol. Even when the monarchy returned after Napoleon, they were scared of rolling back too much of the people's gains for fear of starting another revolution.

Point is, they had an emperor and then some kings again, but comparing life before and after for the average French man, after was a marked improvement. The Revolution did work, to a point. I think the lesson more is that with every progressive gains, there will always be a conservative reaction people need to be aware of. The old power structure will always try to regain what they had before. It's not too give up and ask for scraps from the people in power.