I don’t think I understand the question - or, if I do, I’m failing to see the point of the question.
You have no idea where you’ll be in three years. It’s good to look forward and to hope that you’ll still be wearing your nicest clothes then - but maybe in six months you’ll be living a nomadic life in the Sahara … Even if that doesn’t happen, some of your expensive buys may just look wrong suddenly, so you won’t want to wear them. Maybe you’ll change your hair colour or lose weight, or whatever. There are no guarantees.
Also, clothing and fashion evolve - even for people (on MN) who sincerely believe they don’t follow fashion. What will be valuable to you in three years is clothes that look cool and current and zeitgeist-y, and that suit your lifestyle at that point. Maybe in three years you’ll own three £1,000 suits and then move into your dream job where everyone wears shorts and t shirts and an apron every day …
On the other thread I mentioned that I’d bought a jumper this week that will work perfectly with a skirt bought three years ago. But it wasn’t a plan; I didn’t know I’d want the jumper back then. It’s happenstance, or serendipity.
My advice (after over fifty years of choosing my own clothes) - get to know what determines quality in clothes so you can separate the good from the awful; invest a bit of time regularly to look at the best of what’s available - online is probably easiest unless you’re in a capital city; buy what you love and want to wear, either for years or just for now. And look after your clothes, so they’ll last.
What to buy, and from where, are a separate question, depending entirely on your lifestyle and clothing requirements.