They weren't implying that, see the quote they included. OP said they hadn't seen profit margins this high, and the reply indicates that it's not uncommon to see software even higher.
It's just a useful tidbit, related to the point they specifically quoted.
Though perhaps you could say they sell derivatives of software products?
I'm assuming they write the best custom chip design software and that's their biggest competitive advantage (and then operational excellence and savvy business maneuvering et cetera). Though I know nothing about them just guessing as an outsider.
TSMC doesn't really write chip design software. Maybe they do at some small level but that's not their bread and butter. TSMC provides IP engineers need to design chips to be built by TSMC. That IP is used by CAD tools from major players like Cadence, Synopsys and Mentor (now Siemens, I guess).
TSMC's advantage is their superior chip fabrication technology and ability to scale.
You will also need to look at R&D spend and CapEx. Those profits are funnelled back to that. Basically it is a whole cycle, in order for fat profit margin you need to be at the leading edge in Tech, Yield and Volume. And all three of those requires R&D and CapEx. So you need Fat Profits margin to sustain it.
Meaning what? The factory gets destroyed? A competitor appears? Labor costs rise? Demand falls?
So long as the world economy is dependent on the TSMC, a CCP invasion seems unlikely if that's what you mean. The profitability isn't the clearest way to measure that. It could fall for a number of reasons without the geopolitical context changing.
Should TSMC fail due to one of the causal factors being geotech political interference on the horizon from the clash of China's Communist Party and the U.S. Wario Blob mic you would think ASML has wargamed plans to supply demand.
Aren't they profitable because they are in a unique position? I would hope they keep being profitable. What happens if they would fail?