However, I agree with Wren, in that there are times when older kids/adults tolerate the presence of a gifted kid better than kids who make an issue out of their differences. But there may not be true friendship in mere tolerance.
I wouldn't be so quick to reject the role of 'mascot' for a child who finds that they are years younger than their intellectual peers. Depending on the needs of the child, this may be a very satisfactory arrangement. Human relationships are complex, and pretty much everyone relates to everyone else in an individual, specific way. Some kids wouldn't want to be in the mascot role, but some really enjoy it.
Food for thought,
Grinity