Why not? Basically you can look at maps over the years and see the British chip away at French colonial possessions one by one throughout the 1700s.
The French at one point colonized the entire lesser Antilles in the Caribbean and by the mid 1700s they were left with just four or five islands.
Why not build their navy to compete with their arch nemesis? Why let the British outperform them by so much for so long?
The French had a land border with the Holy Roman Empire, Spain, and wanted to pursue expansion of French power in Italy. All of these things made land forces more important than sea forces.
For the British, after the Hundred Year's war and the fall of Calais about a century later, they had no desire to expand land holdings on the European continent.
Also, once the Crowns of England and Scotland joined, they no longer had any land border on their island