This post really blew my mind away.
You are 30, with a university degree (in chemistry in a country with a flourishing chemical industry), a job, and a decent salary. You have a lot in investments, you drive a great car, you're in good shape overall and for someone from a poor background YOU ARE MIDDLE CLASS ALREADY.
There are a few things I'd say.
Try getting a management degree as well, an MBA or something like that. It could help you to move to other roles in senior management and that is where more money and adventure are. You could also try high risk stuff like Angel investing but like I said, it is very high risk and requires very advanced analytical skills to figure out the best ventures to get into.
Know that life is a war and like any war the earliest winner is the one who is best equipped and the earliest winner is not necessarily the only one, others can win too.
You want a big house with a garden, a big parking, even a home gym. A garden is not that extravagant but a domestic gym? Those are houses bought by very highly paid professionals like doctors, high end lawyers, top managers, politicians, high end engineers, heirs to immense wealth from parents (like your friends),.... people who in their mid age get net salaries well above 200% of the average salary which means a gross salary that is very high especially in high tax countries like Belgium. You want to live the life so many are fighting to live and since life is not forgiving it is probable that people in your generation who didn't waste time will beat you to it. Maybe one day you might own such a place, but unlike that surgeon you see at the hospital it certainly won't be in your 30s but in your late 40s and I don't think you want to retire with a huge mortgage on a house worth well over 600,000 Euros (unless somehow you will be getting paid a gross salary well above 84k Euros a year). To add to this, you want to do this alone, this is not 1970 when one income could do miracles, even married couples with decent jobs would struggle to afford a luxury house and a 2022 Mercedes while making investments, saving for retirements, keeping up with rich kids with great careers,.....
As someone from a poor background, you are in a phase of creating generational wealth and from what you said it is going well for you, you ought to sit back and look at how far you came then drink to your incredible journey. Those friends of yours have parents who did that for them, you are doing it for yourself in your old ages and for the children you will have if you do. Keep on investing, saving, get more education, and fight for promotions, you will retire in better shape than probably 90% of citizens in the developed world (you have an investment portofolio most people even in the USA don't have, that is amazing). If you ever decide to have kids MAKE SURE THEY STUDY HIGH INCOME SKILLS, make sure they do very well at school because they won't be trust fund babies that will inherit hundreds of thousands or millions, orient them towards fields that will land them in banking or engineering or medicine - high paying fields that give a kid with limited family connections a fighting chance. They say "let kids choose" but that is crap, you orient a child towards something that will pay the bills and I'd bet that the kid will thank you for it when they are in their 40s taking their kids to a ski trip in Switzerland.