How can Insider Pressure Groups have more Chance of Success, but also Not have Any Effect? (EX)

Yay: Insiders Groups may have Opportunity to have their Views on Legislation. Example: Private Healthcare Companies had Helped in drafting the Health & Social Care Bill which had Benefited them Nay: Not every Insider Group is Influential is Circumstances. Example: The CBI has Strong Ties to Conservatives but has failed to Influence Government Policy on Brexit to the CBI Interests