Understanding the last lines from Oscar Wilde’s The Model Millionaire

Question

The Model Millionaire is a short story about a young man, named Hughie Erskin, who although does not have much money himself, is moved to pity by the sight of an elderly beggar who is posing as model for his artist friend. Although, he can barely afford to do so, the young man gives the beggar the largest denomination coin that he has in his pocket. The young man’s act of kindness earned him ten thousand pounds.

The old beggar was Baron Hausberg, and it was him who sent Hughie the sum of ten thousand pounds. But at the last of story the Baron made this speech

Millionaire models are rare enough but model millionaire are rarer still.

I really cannot understand what he wanted to say.

Answer 1

The question is wrong about who makes that speech at the end. It is not the Baron, but the best man at Hughie's wedding to his fiancée Laura:

When they were married Alan Trevor was the best-man, and the Baron made a speech at the wedding-breakfast.

'Millionaire models,' remarked Alan, 'are rare enough; but, by Jove, model millionaires are rarer still!'

Alan is the artist who painted the picture of a beggar using the millionaire as the model. He has told Hughie that models make "a shilling an hour" for posing. This is obviously not something that a millionaire would find lucrative. So it would be rare to have millionaire model—someone who would find it worth the bother to pose for a picture just to earn one shilling an hour. Hence, millionaire models ... are rare.

The Baron's behavior shows him to be a generous person who also has a sense of humor and who can appreciate the good in others. Instead of being offended for being mistaken for a real beggar, he rewards Hughie for his generosity and even attends his wedding. This makes his behavior exemplary, i.e., he shows what all millionaires should be like; he models the behavior other millionaires should display. Hence he is a model millionaire. Since most millionaires are not like that, they are rarer still.

In other words, what Alan is saying is that one is less likely to find a generous, witty, and appreciative millionaire than to find a millionaire willing to pose for a picture. The Baron is two very rare things, a millionaire model and a model millionaire.