You don't need to be highly intelligent and skilled to be a terrorist. All you need to do is set light to some explosives which frankly can be found pretty much anywhere near cars or home appliances. You could probably bring down an entire building just by using your gas storage. The entire population of France taking up police work would do little to stop terrorists that we can't find until they've done the job which is quite easy to do.
Much of France's response to the country's recent terrorists attacks has been merely for show. The French government has yet to show that it is serious about defeating ISIS on the battlefield. Until France and other nations commit the military resources necessary to defeat ISIS, terrorists attacks like the one in Nice will continue.
Hollande is definitely under fire for the recent attacks on France. People are complaining (more specifically the people of France) that Hollande is not using his resources correctly, that he is not doing enough. I am not surprised. Until France starts doing something about the problems that it's been facing, attacks will continue.
France has suffered terrible loss of life at the hands of Islamc State extremists with attacks on innocent civillians. Hollande is aware that these attacks by small terrorist cells and lone wolves are encouraged by the leadership operating in Iraq. By supporting Iraq military, he can help eradicate the extremist leadership, cut off the supply of arms and stop the training and radicalization of jihadists. In the long term, this will hopefully prevent further atrocities on French soil.
While there may not be an end to the Isalamic State extremists, as they have been around in some form or another since biblical times, France will try hard to stop them. After the latest terrorist attack, the French have had enough and they definately want an end to these attacks.