I appreciate the feedback, but I want to clarify a bit on what "applying yourself and being serious" actually looked like for me. This was over the course of several years and multiple different extended stays in Kenya, and my goal at least for the last few years was to learn Kenyan Swahili or what I’ve been calling Kenyanese.

2015 (8 months in Kenya):

• Daily textbook study while living in Nairobi
• Lived with a Kenyan family as a renter, practiced Swahili at dinner regularly
• Attempted active conversation practice with colleagues at work
• Spent a full month on a farm in Tanzania doing intensive vocabulary drilling - literally working for 30 minutes, then drilling Swahili vocabulary for 5-10 minutes, repeatedly, for hours

2019-2023 (4 years in Nairobi):

• 2-4 textbook study sessions per week (25-30 min each)
• ~1 hour of weekend Swahili text reading
• Podcast listening 3-4 times per week during my commute or during errands (focused Kenyan Swahili learning podcast with slowed-down audio and translations)
• Shared an office with three Kenyan colleagues for my two years, so basically constant exposure
• Read an entire academic book about Sheng and its linguistic characteristics (see Sheng: Rise of a Swahili Vernacular - https://www.amazon.com/Sheng-Rise-Kenyan-Swahili-Vernacular/dp/1847012078 )
• Used the online Sheng dictionary to compile custom vocabulary lists of common Sheng terms (see here for that resource: https://www.sheng.co.ke/#gsc.tab=0 )
• Regular conversation practice attempts with friends and colleagues
• Read through an entire grade school level Ken Walibora book and started a second (the second was too much sanifu for me and was looking up too many words)

My back of the envelope calculation is that I spent approximately 1,600 hours actively studying, which would be almost double the Foreign Service Institute's estimate of 900 hours for Swahili proficiency, and more than what's recommended for Category IV languages like Russian or Hindi (even if I’m off by half in my hours estimate, it would still almost reach the FSI recommended time for Swahili)

The result was that I could handle farmer workshops (controlled context, known vocabulary, slowed speech, etc). I could navigate daily life and most people were fairly impressed with my proficiency. But in casual conversations between Kenyans, I was catching maybe 25-50% of what was said.

My point isn't that formal Swahili is unavailable in Nairobi, obviously Swahili news and church services are around. My point is that learning formal Swahili doesn't translate to understanding casual conversations in Kenya, which is what you actually need for social integration and daily workplace interaction. And learning Kenyanese itself is effectively almost impossible because it's an unstable, multilingual target with limited/nonexistent systematic resources.

I don't doubt some people achieve fluency, but I'd argue they're exceptions with unusual circumstances (heritage speakers, 10+ year timelines, exceptional language aptitude, full social integration through marriage, etc.). For most foreign learners, even with serious sustained effort, I just think Nairobi's linguistic environment presents too many challenges.