OP you are making an assumption that a solicitor won't move forward with a case that has a low chance of success.
This is incorrect. A solicitor gets paid irrespective of the outcome. The only difference may be who pays them.
As has already been posted, if you proceed and fail there is a likelihood of you being liable not only for your costs but that of your brother.
You also mention other family members are encouraging you to contest the will. It's all very well for them to stir the pot, but they have no skin in this and unless they are proposing to pay your legal fees then you need to cancel out their "noise".
I don't think you are greedy. I think you rightly feel a strong sense of injustice, betrayal and hurt but I think that's clouding your judgement.
You talk about what the Judge's alarm bells being raised by your brothers behaviour - but it doesn't work like that. Ignore alarm bells - you could have a siren but it makes not one iota of difference if you can't categorically prove something.
Trying to prove your mother was manipulated will be virtually impossible. You say they cared for her to coerce her and save fees. Your brother says your mother changed her will in gratitude to them for looking after her in her final months...neither can "prove" their version in true but your brother unfortunately has what appears to be a valid will on his side.
The fact it's unfair to the younger children isn't relevant. Wills don't have to be fair.
The fact it's not what your father wanted is irrelevant. He had the opportunity to make his wishes known in his will and left his assets to your mother to dispose of how she wished.
Your mother made a new will at the end of her life - that's not unusual nor is the fact she changed her mind about how to dispose of her estate. She was within her rights to do this.
By all means speak to your solicitor but please be realistic about how much this is going to cost you and don't assume the solicitor has your best interests at heart.
I'm not a solicitor but have been involved in a family will dispute and based on what you have posted would suggest that your best chance is to threaten legal action to try and gain a settlement via mediation with your brother, but not to actually pursue it and hope he doesn't call your bluff.