The french believed that
For a simple reason, eveything else was occupied. England had the US, Portugal had Brazil and Spain what is now most of South America. The French did indeed try to settle in these colonies but they were massacred. King Francis the First was reluctant to settle North America because the Pope had divided the world into 2 sections one belonging to Spain and the other to Portugal. Francis 1st wrote the Pope who told him that only applied to land ALREADY discovered. So France had the go to colonialize what was left... Canada.