The Empire wasn’t what made Britain wealthy. Given the expenses incurred in garrisoning and running the colonies, it was probably run at a net loss. Being the pioneer of the industrial revolution and becoming the workshop of the world made Britain rich, just as it did Germany later in the 19th century (despite its minimal colonial Empire) and the US, and now China....
I’m not so sure about that. The army wasnt everywhere. The problem with the colonies was not that they didnt make a lot of money, or even that it cost very much to garrison and run them. The real problem was that their very existence tended to tangle Britain in wars.