Continuing from original numbers:

1. The most direct answer is most of the people of Eastern, Central and Southern Europe. Draw a circle from Estonia, to Czechia, down the east Adriatic coast, around Greece and Georgia. That's a lot of people and a lot of peoples. Many have immigrated to the US or western Europe and have established lives in the multicultural societies where they (today but not always historically) get counted as "white".
The more complicated answer would also include some peoples from Central and South America. Many peoples there who consider themselves "white", through evolution of cultural identities after colonialism. It's not as simple as "Oh, well there were white colonizers and everyone else" -- the "mestizo" identity has grown and changed but it's very much it's own thing.
Finally, even among the obviously-colonist nations, there have always been underclasses who had no say in managing their societies or what those societies did overseas. This observation is anathema to those who want to draw neat circles around societies and label them colonizers, racists, etc... but as a simple matter of fact, there plenty of super "white" British/French/Dutch/etc people who lived at the height of colonialism and still had nothing to do with it, whether they would have wanted to or not.

2. Sure, it's relevant. But, again, the discussions of how accurate it is to make sweeping claims about "white" people or countries do not necessitate any kind of colonialism denial. This was in response to your comment upthread which implied that discussing the harms of "white = prejudice + institutional power" necessitates ignoring colonialism. It doesn't.

3. Helpful clarifications, but you didn't respond to the arguments.
A) "Current elites" are diverse, both within multicultural societies like the US and around the globe. Maybe that distribution isn't "perfect" (begging what that would mean...) but it's factually wrong to call those elites, as a category, white.
B) 15th-19th century colonialism was a continuation of the prior state of the world (across cultures, societies, geographies). The unusual thing was the technology that propelled it to a larger scale, as well as the subsequent phase change in civilization (caused by industrialization and globalization) which ended those norms of dominance and conquest.
C) It's an extraordinary claim (though extraordinarily popular in the canonical liberal-progressive worldview) that extractive colonialism was the sole (or even primary) driver of current inequalities. Those gaps were already huge when colonialism started (and hence why it worked so effectively). Culture (at various level of 'zoom' with respect to that concept), education, technology, social values... tons of things play a role in differential development. To group all current disparities and wave your hands while mumbling "something something colonialism" does not establish a rigorous model of what causes differential development.

To sum it all up:
It's a simple fact that lots of "white" people had nothing to do with colonialism, nor even had an opportunity to design or perpetrate any colonialism. That alone makes demonizing the category with moralizing labels a harmful decision.

Add the much more complicated subject of determining what drives or has driven disparities in various cases, and it becomes extremely questionable to claim that "white = prejudice+power" is a necessary or even useful tool for analyzing social relations and designing solutions.