If the settlement of the Claim results in the insured being in a better financial position than he was before the loss occurred, the extent of the improvement to his position is known as ‘betterment’ and he would be expected to contribute towards the Claims settlement.
Your hi-fi set is destroyed in a fire. A replacement similar to the hi-fi you had would be R5 000. You prefer to upgrade the hi-fi to a set with value of R7 000. The R2 000 difference constitutes betterment and would be your own account.