>>213441288You're severely overblowing the cost of transportation and naval maintenance. The British certainly didn't consider it that high if they regularly shipped their convicts halfway across the world or stationed their navy off the coast of Africa just stop the slave trade.
https://en.wikipedia.org/wiki/West_Africa_Squadron
As for it being worth it in the long run for the common Englishman? Well that's a whole nother conversation. I personally think it wasn't worth it for the English and the only nation that actually benefited from colonisation in the long run were the Dutch. That is talking about even the standard of living in a post-ww2, pre-mass non-white migration England. Not to imply that mass importation of browns is a direct result of colonialism, which it isn't.