Even if accurate (and there’s absolutely no way to know, as download and IAP data is not available to third parties on iOS), that number is disturbingly low for one reason:
revenue ≠ profit
What we really want to estimate is profit:
profit = revenue - expenses
Let’s see how far $400K goes, if we just take salaries into account:
SEMC has approximately 80 employees. If they generate $400K per month, that’s $5000/employee/month and only $60K/year … extremely low for even an entry level engineer.
But salaries aren’t their only expense, of course. They have to pay Amazon for storage and data transfer, contractors for artwork and such, rent or mortgage on their offices, insurance, legal fees, electricity, water, and garbage collection, etc.
Last but not least, income (profit) is subject to taxes. The US government levies a tax of up to 21% on corporate income, for instance. California, where SEMC are located, adds on over 8% more.
So tbh, that tweet is actually distressing evidence that SEMC are in big trouble.
[EDIT: I originally wrote that “revenue is subject to taxes” – which is inaccurate: income is subject to taxation. (H/T to @TheCopyCat for catching that mistake.) Income is revenue - expenses, and taxes would be taken out of that to give you profit.]