If Napoléon successfully commits suicide, there'll be no 100 Days, which will mean that France will not be forced to sign the new, far less favourable, 1815
Treaty of Paris, which had more punitive terms than the
1814 one. France would not have had to pay 700 million francs in indemnities, and the country's borders wouldn't have been reduced to their 1790 status, rather than 1792 as in the previous treaty.
France wouldn't have been occupied by 1.2 million foreign soldiers; with said occupation continued until 1818, by around 200,000 soldiers under the command of the
Duke of Wellington, and France wouldn't have had to pay the costs of their accommodation and rations, on top of the reparations.
The promise of tax cuts, prominent in 1814, which failed to materialize because of those payments IOTL, could have been implemented. There also wouldn't have been the second White Terror and, among others, Maréchal Ney could have continued to serve his country. The legacy of this failure, and of the second White Terror, left Louis XVIII with a formidable opposition IOTL.