Glorious promise

"No man shall be able to stand before you all the days of your life; as I was with Moses, so I will be with you. I will not leave you nor forsake you." Joshua 1.5

This same promise was also made to Abraham, Isaac, Israel and Moses. Now it was Joshua's time. In every age, the chosen of the Lord are assured of His constant presence. There is no jewel or treasure in the entire universe that can be more precious than this. His presence has been with all those who are with Him. But those who despise Him are lightly esteemed.

Guarantee of Salvation

"...you were sealed with the Holy Spirit of promise, who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory." Ephesians 1.13-14

Sealed with the Holy Spirit, guarantee of inheritance, redeemed possession, and the praise of His glory. In practical terms, the seal of the Holy Spirit is the GUARANTEE OF SALVATION of His servants until Jesus comes to rescue them. Just as jewels guarantee a loan, the servants of God are the jewels of His Private Treasure. To ensure that these jewels are untouched while they are temporarily serving in this world, He sealed them with His Spirit until the day of his final redemption.

Answer

"Those by the wayside are the ones who hear; then the devil comes and takes away the word out of their hearts, lest they should believe and be saved." Luke 8.12

The devil can steal the Word of the heart because, despite hearing it, the person still did not care, they were not interested, they despised it and gave it no value. They did not care for it because, in their eyes, it wasn't that important. Who would neglect a precious jewel?
For each four people who hears the word, at least one of them despises it.