CornishMaid- no, I don't think people should be allowed to invest exactly how they like, if that choice plainly disadvantages others. That's socially divisive.
I think one thing we overlook is that there aren't, particularly in the S/SE of Britain many people who own more than one house who didn't get some sort of leg up onto the housing ladder.
We didn't all 'work our socks off' to get there
It may have been able to buy at an opportune time (like when a mortgage could only be taken out in one name, and houses generally cost a 2.5 to 3x multiple of that person't annual salary): it might be coming from a family able to support you to get into uni, to get a degree and a ££ job; it might be being able to get a 100% mortgage; it might be a parent gifting the deposit; it might be inheriting from parents; it might be 'marrying well'.
I:
-Sold the house my parents bought in 1969 for £4,500 for £450,000 in 2016. Dad certainly didn't 'work his socks off' in his 9-5 middle management job; retiring at 57...
-Overseas, married a bloke who due to that country's mortgage arrangements (typical was 7 years, then!) who'd more or less finished buying a nice flat in a popular city.
-Went to a grammar school
-Had parents who supported me into a professional job.
Fair bit of 'luck' in among my 'good judgement' in there!