The point is, when someone has offers from other companies for 10% increase (which imo is pretty low usually it is 20% or more), the employee finally realizes their value.
In these situations often the employee is getting raises that do not even cover inflation. So the employee now sees their market value and would like to continue working for the company, but they have realized they could take on risk for a 20-50% raise instead.
I mean the risk equation is simple, with such a raise you can save enough cash to justify the risk even if it doesn't work out.
I always ended up taking the offer from the more generous company, and they tended to increase my pay to offset more than inflation and then a bonus to justify staying.