Compared to other European cuisine, Italian is (in my experience!) by far the most popular around the world. Italian restaurants far outnumber Greek, French, German, etc. in North America and even in Europe it's easy to find Italian food in various countries.
How did this happen? I remember reading in various historical and fictional period texts in which characters express their disdain for Italian food. What caused the widespread adoption of it as the 'go-to' cuisine?
The answer relies upon a combination of human physiology and economics
Italian food contains large representations of foods with high Umami content. Tomatoes, fish, shellfish, aged cheeses, etc. This food property (not truly a "taste" but equivalent) was relatively under valued through much of human development in favor of tastes that represented other more necessary nutrients--ie fat, salt, protein, etc. As human society transitioned out of subsistence nutrition into sufficiency nutrition those cultural cuisines with umami rich diets were preferentially adopted.
With this was the economic collapse of the southern Mediterranean that occurred in the 19th and 20th century. This served to impel a large human exodus from the region (not just Italy, but the entire region) with propagated the culture of the region, including diet.