The priests and religious leaders press on with their plot to get rid of Jesus. Two points stand out in this passage: scheming and secretly. If Jesus had actually done anything wrong would they have had to keep their plan undercover? They simply did not appreciate that He challenged their authority. Jesus revealed the religious leaders were a sham, and they would not have Him challenging their authority anymore.
What made Judas want to betray Jesus? Judas was the treasurer of Jesus's ministry. He was a thief according to John 12:6. He helped himself to a little extra out of the money bag, which Jesus knew about. Both in Mathew and Mark, there is another event that happens between these two passages.
John places the event prior to Jesus's triumphant entry into Jerusalem on Palm Sunday. Both Mathew and Mark place the passages right before Judas betrays Jesus, most likely so we can immediately see Judas's character. He viewed the woman's act of worship as a waste of money. Money the perfume could have been sold for to potentially line his pockets. He did not care about the poor as he claimed. He missed the importance of Jesus being anointed in preparation for His burial. Once Judas realized that Jesus was not leading a political movement where he could gain wealth and status, Judas turned to the people who could.
Ultimately, Judas allowed his own earthly desires to take precedent over what was right. It would be easy for us to judge Judas, but we are all guilty of allowing our desires to cloud our thoughts and alter our motives. Jesus chose Judas as a disciple for a reason. Judas had the opportunity to choose a more honest path with Jesus, but he made the choice to not change his ways or his heart. Judas does come to deeply regret his decision to betray Jesus and returns the money "for I have betrayed innocent blood." (Mathew 27:3). He was so overcome with remorse and hangs himself after Jesus was arrested.
Judas could have repented, and he would have been forgiven. If Jesus could forgive Judas for betraying Him, He surely can forgive us for anything we are truly remorseful for. He is a perfect example for us that we need to be careful and aware of our inner desires. Just because he was a disciple, didn't make him anymore of a follower or believer. If Judas could be closed off to Jesus even being in His inner-circle, how much more could we?