divide it like sumptu+ous;just focus on the SUMPT+U,SOUNDS LIKE SAMPAT(I)(IN HINDI..DHAN SAMPATI)SO SAMPATI MEANS MONEY,well if you have a lot of sumpati or money, you will spend it LAVISHLY,you will be able to buy all luxury.
just focus on SUM(means whole amount)+ptuous.....well you have decided to spend whole amount of yours ( around a crore )on your wedding..so you are trying to be sumptuous.
akin to consumption, presumption, assumption. <br>consumption = take in <br>presumption = taken, before hand <br>assumption = taken as sumptuous = something that takes a lot.
A rich, SUMPTUOUS meal is also SCRUMPTIOUS(delicious).