Yes, there are Chinese by origin but slowly losing their ethnicity. Many Indonesian Chinese can only speak Indonesian; Thai Chinese can only speak Thai. Some don't have Chinese names anymore. So far, the Singaporean and Malaysian Chinese can still speak Mandarin because the Governments are not forcing them to be neutralised.
They are rich for one reason, they are thrifty and they are hardworking; most of their ancestors originally came from Southern China when there were famines and they were generally very very poor.