T-Mobile earned $8 billion in 2023. Some division later, that works out to $21,000,000 per day.
They were fined less than one day's income. If I owned that company, increasing IT security would be near the bottom of my list of priorities.
To your point, $16M is surely not a big fine for such a big company though, but I do think it's important not conflate profit and revenue when evaluating fines.
Generally speaking, I would love to see some much harsher penalties for negligence with data. I want companies to start seeing customer data as a liability, not as an asset, and I don't think that will happen until f**k-ups starts really making a dent in the bank account.
Profit, their revenue is almost 80 billion. Fines like this should be certainly based on revenue rather than profit, though (like the EU does it)