I was born in what was then Yugoslavia (now North Macedonia). In order to get a good full perspective of this issue I think you have to talk to several Greeks and North Macedonians. This has been my perspective and experience: It's mostly split between the population -- half (probably most) of us don't really seem to care about this issue, the other half feels pretty upset about it. It's really important to note that…
The term 'Macedonia' does not refer to a geographical region only. It refers to a geographical region plus the connection to ancient Greece.
Slavic people like you have no right to use the term Macedonia, because you are not related to Macedonia, the ancient-Greek derived sub-ethnicity. You only live in Macedonia, you are not a Macedonian.
History is full of examples of people that moved to other areas but did not 'steal' the history of the area they ended up into.
Turks moved to Ionia, they didn't become Ionians. Greeks moved to Pontos, they didn't become Turks. Spaniards moved to America, they didn't become Indians. British moved to Australia, they didn't become Aboriginals.
Just because your progenitors moved to the area of Macedonia, that does not entitle your people to claim they are Macedonians.
Yes, you are a separate people, you have your own culture, language, you have become a nation, and we, Greeks, certainly recognize that.
But claiming you are Macedonian and you speak the Macedonian language? that's a fallacy. You should just use another term.
I am saying all the above in friendly spirit and with the relevant historical sciences in mind. I am not a Greek nationalist, I only want justice. And in this case, judging from the historical records, justice means you Slavic people are not entitled to use the term Macedonia in any form.
The ancient Kingdom of Macedonia was 100% Greek, judging from the historical records, the written works, the names of places and people, the language used, the art forms, and the fact that the rest of Greece accepted Macedonians as Greek.
Beyond justice, what might be the reasons for us Greeks not wanting other people to take our history? well, here are the reasons:
1) there is the danger that, in the future, the connection between North Macedonia and Greek Macedonia becomes the geopolitical cause for an unforseen yet block of power to change borders in the area.
History is full of examples of geopolitical blocks using specific interpretations of history, culture and geography to cause problems.
2) Greek products from Macedonia can no longer be named 'Macedonian' in other countries.
I understand it's difficult for you to accept it, but you have been actually scammed. From the moment you were born, to now, in all your life, you have been indocrinated to believe you are Macedonian, that you speak Macedonian, etc. What a shame! this has been done for political purposes.
If only you could let the notion that your people and any form of the word Macedonia has any connection, the world would be so nice!!!