The 'rechush gadol' - the substantial wealth that was promised to the Yidden when they would be redeemed from Mitzrayim, requires explanation. Taking into account the bitter exile they were enduring, one might recommend that it would be better let the Yidden leave earlier with no wealth, than to wait out the entire exile and then leave with great wealth.
It must be that the wealth that Hashem promised to the Yidden wasn't just a payment and appeasement for their hard labor, which the Yidden could decline for an earlier freedom, rather it was the purpose and endpoint of the golus. If the Yidden would have forgone their promised wealth, the purpose of going to exile would not have been realized.
The explanation of this is; when wealth is viewed as personal possessions and comforts, then the argument can be made that it's better to be free than to be a prisoner with wealth. But when wealth has a greater purpose and goal, it's not so simple to forego the wealth, because it's not just the wealth being forfeited, but the ultimate purpose is also being forfeited.
When Hashem promised Avraham Avinu that at the end of the exile his offspring will leave Mitzrayim with great wealth, it was with the goal of the Yidden elevating the G-dly sparks contained in the great wealth. This is accomplished by utilizing the wealth only for the purpose of connecting to Hashem through Torah and mitzvos. One's intention when eating is in order to have the energy to serve Hashem. Every activity is done only if it is congruent with serving Hashem. Thus the great wealth was being promised to the Yidden in order that they utilize it for divine purposes.
Hence, if the Yidden were to be redeemed earlier on the account of not receiving the wealth, there would be a tremendous loss of opportunity to elevate G-dly sparks which would have otherwise been elevated.
This is an important lesson on how to deal with materialism in general, especially when it comes in abundance; Hashem is giving the person an opportunity to achieve great accomplishments if they choose to approach their heaven sent possessions with spiritual intentions. The wealth has no meaning on its own, and should be treated that way.
This conduct may require constant reminders and strengthening, and ongoing study of Chassidus, especially if it's in depth, will surely fortify these intentions and ensure that they will be acted upon.
 Likutei Sichos vol. 3 Parshas Vayigash.