Tikka masala and butter chicken are big in the west because they’re British dishes (literally invented by Indian chefs in England).

They use less spice, more cream, more coconut, less chilli, less garlic, less ghee and fats + added meat. They’re much more bland compared to real Indian food - all of this was designed to make them more palatable to British people who aren’t used to hot spice and pungent flavours, which is cool I guess because it caused a huge explosion of Indian food and now it’s the most popular cuisine in the U.K.

Then from here I guess it sort of spread out to Europe and America. But yeah I wouldn’t count those dishes and “real” indian food either, but it’s a good gate way into the real stuff.