Sinhalese is primarily spoken by the Sinhalese people of Sri Lanka, who make up the largest ethnic group in the country. As of my knowledge cutoff date in September 2021, the population of Sri Lanka was approximately 22 million people. Around 75% of the population, or roughly 16.5 million people, are Sinhalese. Therefore, it can be estimated that around 16.5 million people speak Sinhalese as their first language. Additionally, there may be some speakers of Sinhalese in other countries as part of the Sri Lankan diaspora, but their numbers are relatively small compared to the population in Sri Lanka.