Well, take it from somebody who successfully built and sold a startup and worked in M&A...
If you have zero growth and whatnot - yeah, 25x on EBIT may sound steep. But software can scale w/o much incremental costs (given what the author mentioned).
If you assume they know their business (you know, those MBA kind of guys...) and see a 30-40% yoy growth in revenue with a rather fixed cost base - what exactly does your calculator tell u?
10x on sales and 25x on EBIT isn’t exactly greedy... Look at FAANG valuations...
You can also do some back of the envelope math with discounted FCF. Take a 15% discount factor and 30-60% yoy growth (if you don’t see something like that or anticipate it - it’s not worth much tbh).