Sham grew up in a single-parent family and completed secondary school in 2006. He worked as a legislative assistant for a period after graduating from secondary school. He later joined Rainbow Action, a member organisation of Civil Human Rights Front which advocates for LGBT rights. He started assisting with the work of CHRF in 2008, such as by hosting events and managing affairs with human and police rights. He occupied Connaught Road Central along with other protesters after the July march in 2011, after which he was arrested for unlawful assembly. He participated in the 2014 Hong Kong protests and became CHRF's convener in 2015, for a period of one year.
After Sham left the post of convener, he studied at the , graduating in October 2018 with a Higher Diploma in Social Work. He immediately rejoined CHRF, again as convener. This came at a difficult time for the organisation, as it had only HK$300,000 in funding with a monthly expenditure of HK$20,000. He is a long-time member of the League of Social Democrats and he joined its executive committee in 2018. He first joined the political party because it was the first in Hong Kong to include LGBT issues in its platform.
Sham is openly gay; he married his husband, a flight attendant, in New York in 2014. He is an active campaigner for LGBT rights in Hong Kong. As a secretary, he manages daily operations for Rainbow of Hong Kong, helps organise annual LGBT rallies and hosted an LGBT programme on Citizens' Radio. Sham was also the spokesperson for the 2018 Hong Kong Pride Parade, which drew 12,000 people, a record high.
2019 Hong Kong protests
As convener of Civil Human Rights Front, Sham helped organise the first and second protest marches against the on 31 March and 28 April respectively, as well as helped organise the protest march against the bill on 9 June. The number of participants at this march exceeded Sham's expectations: although CHRF set a target of 300 thousand protesters, he estimated that more than a million people participated in the march. On 13 June, following the Hong Kong government's announcement of their intention to restart debating the bill, as well as the clashes at the Legislative Council (LegCo), Sham decided to organize another protest march on 16 June, which meant they had only four days to advertise the planned protest. He estimated that there were close to two million participants at 16 June protest. In an interview with
Citizen News, Sham noted that CHRF itself is unable to mobilise a large number of people to participate in protests, and that the high number of protesters in the 2019 protests was caused by public awareness and poor governance by the Hong Kong Government. He described CHRF's role in the protests as providing a platform for citizens to express their views. He said that CHRF estimates participants at protests by having volunteers count the number of participants from footbridges. Sham organised the 1 July march in 2019, demanding a full retraction of the amendment bill and for Chief Executive Carrie Lam to step down.