I was thinking about this the other day as I get closer to retirement and will likely spend at least a month or two a year in Thailand. I was think about watching videos and learning at least a word a day or week. But then I looked up how many words we know by age and realized in a few years I'd only be up to 3 year old vocabulary
Age Average Vocabulary Size
3 ~3,000 words
5 ~6,000 words
10 ~12,000 words
15 ~20,000 words
20 ~23,000 words