When you murmur about what the Almighty God hasn't given you, you are being unthankful to Him for what He has done. Think about it in the way: If the Lord has given you money to rent a one-room apartment, just thank Him for that one room and He will give you much more. The more you murmur and grumble, the further the Lord draws away from you because He hates the group of complainers.
When the Children murmur about a lack of meat even though the Lord provided manna for. Take for instance that you give your child a phone and instead of the child appreciating your gift, he or she murmurs about it not being internet-enabled then smashes it into pieces. You would definitely be angry.
Now, imagine if the child thank you for that phone, then came after a few days to say, Daddy or Mummy, I like this phone, but if you do not mind, I would prefer one that can browse the internet. You would most likely promise the child that you will get him or her a new phone that will be internet-enabled and then try to fulfill your promise.
A lot of believers are short-changing themselves by constantly complaining. If you thank God for what He has given to you, He will certainly give you more, but if you grumble, then you will get Him angry. Trust God, He wants you to have the best things and He will give them to you at the appropriate time. Things may not be going as you plan them but trust God and be thankful for what He has given to you.
Ambition is good but even as you work hard to be successful, learn to be content with where you are and what the thing you have. He is bringing you to that place you very soon in the mighty Jesus’ name. God bless you