Maybe start at 100-50bbs and have it be a turbo or smth.
Or if this leads to too many abandons you could implement this for higher rankings.
For example; top 5% players could start play at 100bbs, the next 10% could start play at 50bbs, then the remaining 85% of people can start at 25bbs like it is now.
This could allow for the expression of a higher amount of skill in the rankings