It's easier because Python/C++ have huge communities at this point and Haskell does not. It's also easier because most people learn some variety of Java/Python/etc as their first language. So languages with similar structures and conventions are easier to grasp.
Every time someone has suggested I learn Haskell the discussion goes similar to suggesting I learn German. Sure German from a language perspective has some advantages over English in some situations. Some even argue that it's an objectively better language. But I live in Pennsylvania and speak English as a first language. Outside of moving to Germany/Switzerland/Austria, how do the advantages of German provide enough benefit for me to invest the massive amounts of time to become fluent?
Sure if we could turn back the clock on Computer Science education and have everyone learn lisp as their first language maybe we'd all be avid Haskellers these days and be better off for it. But given how history went it is "harder" to learn and less productive to work in due to external factors alone, regardless of how intrinsically easy/hard the language may be (which is entirely subjective).
There's still plenty of value in learning Haskell even if you're not going to use it daily.
I'd go as far as saying it's essential for anyone who likes programming beyond just a profession. Same with lisp.
You don't need to learn all of the language extensions or how to architect serious applications with free as the OP said but it's very useful
knowledge and one of the pedestals from which all other languages should be judged.
Plus you'll understand why Idris and dependent types are an interesting future development in safety and language design. While also understanding the source and inspiration of many features in far more popular languages like JS and Rust. And there may be a real future in it via PureScript and other similar projects.
Every time someone has suggested I learn Haskell the discussion goes similar to suggesting I learn German. Sure German from a language perspective has some advantages over English in some situations. Some even argue that it's an objectively better language. But I live in Pennsylvania and speak English as a first language. Outside of moving to Germany/Switzerland/Austria, how do the advantages of German provide enough benefit for me to invest the massive amounts of time to become fluent?
Sure if we could turn back the clock on Computer Science education and have everyone learn lisp as their first language maybe we'd all be avid Haskellers these days and be better off for it. But given how history went it is "harder" to learn and less productive to work in due to external factors alone, regardless of how intrinsically easy/hard the language may be (which is entirely subjective).