"and you're not making over $150k/yr, you're almost certainly underpaid."
Those salaries don't exist in the UK, no matter your position or the company you work for. I know senior programmers working for Faang companies in London and they don't make this much. Like, in general you won't see a position offering above £100k/year. I know someone with 25+ years experience in the industry and they are on an (incredible for the UK) £90k/year.
The only way to reach the equivalent of $150k/year in the UK is to work as a contractor and be good enough to justify billing that much. As a normal employee you won't see that.
My point is - it's impossible to judge everyone in the world by the American pay standard. Would I make more money in the US? Maybe. Would my standard of living be better? Also maybe, but I lean towards no with this one. But it's almost certainly not true that by making less than $150k/year you're underpaid in a place like the UK.
I worked for a US/UK company with its engineering HQ in London until recently and was earning drastically more than that. Now, I was an early stage employee and doing unique work for the firm. That position wasn't advertised - I created it. But some of the more senior engineers on my team (in the UK) were earning about $150k/yr GBP equivalent, a bit more in some cases.
Are salaries in the UK lower than in the USA, yes, absolutely. They are not that much lower than non-SF jobs in the USA.
Putting aside the question of whether there's an objective standard for whether someone is underpaid - it is not true that nobody in the UK makes $150k/yr as an IC SWE without being a contractor. Filter on the UK: https://www.levels.fyi/comp.html?track=Software%20Engineer
You'll see that mid-level (L4/E4) engineers at Google & Facebook easily break 150k; senior engineers (L5) start at ~225k and hit 300k. That's about 30-40% less than what Google & Facebook pay engineers in SV.
I also saw multiple other companies where engineers with less than a decade of experience were approaching or breaking 150k - Transferwise, Improbable, Palantir, Morgan Stanley, Booking.com, Cloudflare, Bloomberg, Yelp, Babylon Health, Goldman Sachs, Stripe, etc.
My entire network makes more than that in Dev and Arch roles in that part of the world. None of them have to live in London for them either.
Either you're underpaid, or C++ has been commoditized to the same point as PHP. If you value money over language, I'd switch. But given quite a few in my network are Java developers, I doubt language is the issue here.
Well then I have no idea how you and your mates do it. I know people who are in very senior positions at FAANG companies as well as couple big financial firms in the UK and not a single one of them makes over £100k/year. Two of them with PhDs in big data analytics and working in the industry. My own salary might be excused by being in the North East, but they work all over the place, in and out of London.
It sounds like you've got an academia background so if they're research or R&D positions, that might be why. Because they're competing in an already saturated field. Or there aren't many jobs but lots of graduates keen to work in your subfield who will do it for lower pay because they enjoy the work.
If you moved into in-demand fields, service delivery or consulting, you'd see 100k GBP as normal for seniors. The fields only require mastering the tools or domain and the ability to work with business stakeholders. That is from my experience, the majority of the software world.
I don't know what your friends told you, but either you misunderstood them, are talking solely about base (and see my other comment for why >100k base also exists in those roles), or were given inaccurate information. 100k GBP would be 45-60% of the credible range for senior engineer compensation at Google/Facebook in the UK (and maybe 55-70% for Amazon). That's so far outside of the standard compensation bands that other explanations are more likely.
"and you're not making over $150k/yr, you're almost certainly underpaid."
Those salaries don't exist in the UK, no matter your position or the company you work for. I know senior programmers working for Faang companies in London and they don't make this much. Like, in general you won't see a position offering above £100k/year. I know someone with 25+ years experience in the industry and they are on an (incredible for the UK) £90k/year.
The only way to reach the equivalent of $150k/year in the UK is to work as a contractor and be good enough to justify billing that much. As a normal employee you won't see that.
My point is - it's impossible to judge everyone in the world by the American pay standard. Would I make more money in the US? Maybe. Would my standard of living be better? Also maybe, but I lean towards no with this one. But it's almost certainly not true that by making less than $150k/year you're underpaid in a place like the UK.