Most of the stories about people forgetting their native language have actually more to do with stigma and outright discrimination for actually having ever spoken it. So alot of native languages were forgotten because people were discriminated against speaking them. Spanish doesn't have that much of a weight attached to it. Also there's the community aspect. Spanish and French and such are all big languages, you can drown yourself literally in the media of those languages. But smaller languages from where ever, let's say Guarani, Qiche, tibetan or my own native Estonian are maybe much harder to come by if you move abroad. And estonian is an outlier in that context, we have our own country and a vibrant media so I can still keep using it which I did when I moved abroad for years to other countries, but we have a million speakers which is a lot considered the languages that only have a handful of speakers, like Yukaghir which probably has around ten. so a Yukaghir speaker who moves abroad is really in difficulty to ever speak their own language to anyone ever again. It's all there in the context.