That is why a book of voices works where a fourth candle set does not. You ask the people in their life to record a short message, in their own voice, saying what this person has been to them. Their sister. The friend from the first job. The neighbour they have had for thirty years. It costs nobody anything to take part, and it gives the person something they cannot buy and did not know to want.
A few ideas along the same line, from smallest to most involved:
If you go the last route, that is Chorus. You share one link, everyone records from wherever they are, and it becomes a printed book you can hear, read and hold.
The people who have everything are the hardest to buy for, because the usual answer is another object they did not ask for. The gifts that land for them are not things. They are proof that they matter to a lot of people.
A book of voices works where a fourth candle set does not. You ask the people in their life to record a short message, in their own voice, saying what this person has been to them.