My eldest GS is five. An 'only' child, his mum is a divorced high-earning professional who certainly over-compensates with 'stuff' as she is so pushed for time. He seems to have everything and more, and so many duplications. I was a little sad to visit them several weeks after Christmas and notice the bag of presents I'd given him was still under a side table, they'd all been unwrapped in front of me but clearly not looked at since. I always aim for 'something they want, something they need, something to wear, something to read', but this Christmas I'd got extra books instead of a 'need' - there's simply nothing he actually needs.
He goes to after-school club until 6pm because DD is at work. She works on emails and phone calls from home most evenings, so she can rarely actually play WITH him, he's more likely to be watching something on TV or the iPad between getting home, having supper and then bath and a too-late bedtime. He does always have a story at bedtime, and reads his school book with mummy, then his weekend is divided between his parents and they both take him out somewhere, to friends with children, or to the beach or the woods, so again he isn't usually at home to play with any of this stuff. I'm at work in the evenings so I can't even have him after school.
I don't know the answer. Of course he loves to unwrap presents and he is polite with his thanks for them, but I think he is utterly overwhelmed with toys that he'll never actually use. The outdoor things are great, but with a trampoline, bike, scooter, basketball net, battery car, goal net, pool, slide, swing... one is enough. And playing alone isn't always much fun.
But a contribution to his savings account won't make him smile at this age, will it? Nor a ticket to the zoo for some weeks hence. So he'll keep getting more toys and books than he'll ever play with, more clothes than he'll ever wear, and if he ever takes up a super-expensive pastime like horse-riding, perhaps he will actually be easier to buy for!