Computers aren't (relatively) cheap today because Sinclair gave people the idea they could be cheap. They're cheap because of the incremental efforts of thousand of people from research scientists to manufacturing engineers. For instance, the cheaper version of the calculator was built around Texas Instrument's TMS1802NC.
If Sinclair didn't seize on the opportunity to use the TMS1802NC to reduce costs, then one of his competitors would have eventually done it.
You see it happening today. The iPhone launched for $658.38 (inflation adjusted), but today you can buy the vastly superior iPhone SE for half that price. You can go cheaper still if you're willing to go down the Android route.
We didn't need Sinclair to show us that was possible.
Sinclair came to give a talk at our college and explained this was a deliberate and calculate strategy. He sketched a graph showing that maximum profit for his way of working was around a margin of 50%. Unlike most engineers, he was thinking in business terms throughout - while also appreciating the engineering challenges.
It was an excellent strategy for his market, which was mostly nerds and engineers who appreciated low cost access to advanced tech.
Compare the HP and TI calculators with the Sinclair models for context.
There was an engineering-led tradition at HP etc which produced leading edge no-compromise products, but they were sold at leading-edge no-compromise prices. The HP-65 cost the equivalent of >$4000 in modern money.
When you bought a Sinclair calculator you didn't just buy a plastic package with a TI chip inside. You bought the chance to feel a part of a British engineering tradition of cut corners and minimal solutions which nonetheless still sort-of-mostly worked.
You would read about the various hacks and cost saving tricks and think "That's really clever. How does that work, exactly? I wonder if I could that?"
That was the core of the Sinclair branding. It was the ethic that created the ZX series and gave developers and bedroom entrepreneurs a start. It was a scene, and it was the reason he was so influential when more conventional calculator companies - of which there were very many - weren't.
Americans: You have the 'nerd' and the 'hacker', but we have the 'boffin' and the 'bodger'. I'm probably the latter.
No. Nigel Searle, Sinclair's programming and math whiz, actually did it.
Steve Wozniak actually did it.
Archimedes actually did it.
Etc.
I'm not a big fan of Great Person narratives. And yet it's also true that some minds seem adept at finding shortcuts to previously seemingly intractable problems.
How many persons have the actual willingness to defy conventional wisdom, forging progress faster than the mortality rate of the old guard?
Yes - but surely the person who actually did it has to get some credit!
You are missing the point entirely: Sinclair did seize on the opportunity and nobody else did, and likely would not have.
Sinclair did this quite purposefully when in fact if he had been more greedy he could have chosen a different path. And the fact that he did this repeatedly is proof that this was not an accident. So yes, we did need Sinclair to show us that was possible.
"The Sinclair Scientific came out in 1974 and was the first single-chip scientific calculator (if you ignore the display driver chips). It was stylishly compact, just 3/4 inch thick. It originally sold for the price of $119.95 or £49.95 and by the end of the year was available as a kit for the amazingly low price of £9.95.
Unfortunately, as calculator prices collapsed, so did Sinclair Radionics' profits, and the company was broken up in 1979 after heavy losses."
In a nutshell that is both the genius and the curse of Clive Sinclair, he moved markets with complete disregard for the consequences effectively out-competing himself and the would move on to some other field. I always thought that was the best kind of inventor, the one that doesn't care about milking the cows they field, but that democratizes a field to the point that they themselves become obsolete.
Imagine if he had not shown that you can have < $20 calculators or < $100 computers, that would have had major impact on so many people, their careers and the solutions they built that the world would probably look different today.
More Sir Clive, less Zuckerberg and the like.