Asklemmy

So generally you got three things happening that give the illusion it happens way more than it really does. Choctaw/Chinese/White mix btw. Yes that order is weird.

Anyway:

1. White Americans want an identity, and the one they're born with is broken. The US education system really, really fails to define 'White' in any way that makes sense, because as an identity it doesn't make sense unless you're racist. Most white Americans actually do understand this, and either embrace it while secretly denying it, or do anything possible to deny they were the 'bad whites' and that just happens to be their skin colour and then overcorrect and cling onto any identity they can find in their family history which brings us to:

2. They probably are mixed somewhere around 1850-1920. Statistically they are. Lots of what are now white people mixed with brown skinned people during this time. During this time period Natives that were 'integrated' into society had their identity stolen and they were rebranded as either 'mulatto,' 'the old word for black,' or 'Mexican/Latin (if they were in a real fancy area.)' During this time in American history many "white" ethnicities were not considered white, most famously Irish and Italians were lumped in with the 'slur for black people,' which included pretty much all natives at that time that weren't backstabbing their brothers and sisters by sucking up to the whites (not naming tribes but some tribes did end up better than others for some mysterious reason). So guess what happens when a bunch of disparate communities get together? They mix. The mixing was also encouraged by every single christian group in order to help 'mellow out' the native influence (i.e. actual cultural genocide to the survivors of the big genocide). It was also encouraged by a minority of natives themselves, i.e. if you mix with a white person you get their money/protection/you won't be as subject to violence. This was ultimately wrong as an idea and was never a majority view... but it happened.

also rape and forced marriage if they are white but not italian or irish. Statistically that's a thing, especially if they're more than 1/128 and over 30.

That also brings us to:

3. Being native after the 1980s is a good thing, actually. You get a lot of federally guaranteed things, on tribal land at least. For example the only group besides congress which gets free healthcare* are native Americans. You're also seen as 'more legitimate' of an American for some ancestor of yours being here longer, and you generally have a better sense of community and belonging once you're confirmed into a tribe (which can range from actual DNA tests to just finding your ancestor and proving you're related).

For white people that don't care that much and don't want to go through that trouble but want to belong to the native group for clout, just saying they're related gives them that feel good 'I'm a real american, I'm special and not just white, I can't be the bad white because my alleged ancestor suffered.'

To really narrow down the problem, the white identity sucks for obvious reasons unless you want to go full racist. The American identity sucks if you're white skinned, because of the whole genocide thing, also it's too new, too cosmopolitan, and not real to most other people. And most white americans have no cultural basis from their immigrant past because either they had to integrate to survive, it's shameful, or they come from the whites that hated the countries they were from (i.e. the English whites.)

This leads to any attempt to latch onto something they're missing at their core, mainly due to the natural alienation that comes for everyone under capitalism, but especially in a cosmopolitan nation built to integrate everyone under a constructed identity.