In The Boat Of A Million Years, XVIII, "Judgment Day" by Poul Anderson, Hanno the immortal is a millionaire legally avoiding, though not illegally evading, tax, not a figure that I would usually sympathise with. However, in his particular circumstances, his actions make sense:
for all that time, he has had to conceal his longevity from society while trying discretely to identify and contact any fellow immortals (as psychic time travellers try to contact each other throughout history in Anderson's very different novel, There Will Be Time);
during all that time, there really has been no alternative to an unequal distribution of wealth in society;
he has had to provide for his own future security despite all the fortunes of war and the rise and fall of civilizations;
he has prudently stored wealth in places where he will be able to retrieve it at a later date in a different identity as his own heir or successor;
he accumulates wealth for safety and security, not for power or aggrandizement;
he is concerned about the freedom of society, not just about his own freedom of action;
he funds longevity research that may help others;
in the concluding chapter, we learn that the immortals do survive into an era when wealth is so abundant that it can be distributed equally but there is now a danger of social stagnation;
their longer term perspective keeps the immortals at the forefront of human dynamism, inquiry and exploration.
A moral for the novel: we would be well advised to develop that longer term perspective even though we are not individually immortal. If I met Hanno, I would be able to have some interesting discussions with him as do his younger fellow immortals but I would have to respect his accumulated wisdom. We see him gain that wisdom:
he is nearly killed by his own recklessness at about the age of 670;
millennia later, the wily Cardinal Richelieu has to teach him greater prudence.
Another major Anderson character, Dominic Flandry, learns by his mistakes in the Young Flandry trilogy. We see Hanno learning in the same way throughout his single long novel.