Re: Will you kindly stop with the "Britain alone" myth?
All true, the long term war outlook for Germany was bleak (hence blitzkrieg).
It's just that in the summer of 1940 all of the commonwealth & empire armies were small and under equipped, no significant help was likely to arrive before any German invasion attempt. (The Indian army had under 100k troops available for overseas deployment in 1940 and all countries were in the process of rapidly building up their forces)
There was also the worry that the NAZI/Soviet treaty would lead to the red army moving through Afghanistan into India (modern Pakistan) and the Persian oilfields following the successful joint invasion of Poland.
The original Luftwaffe plan was to force the RAF away from airfields in the south-east and gain total air supremacy over the channel, these were the only conditions that the Kriegsmarine would dare sail an invasion force. They knew that with constant RAF fighter cover from nearby fields the Royal Navy would be able to arrive at the invasion beaches in overwhelming numbers and sink everything in the channel (quite literally & regardless of cost) cutting off the troops already landed, without air cover half of the Royal Navy would have been sunk by bombing before arriving and most of the rest soon after.
While it’s a vast simplification to say that the ‘few’ determined the course of history, had they (and all the supporting organisations) failed I’d not like to guess at what the current world order would look like now.